CHEMISTRY 



IN ITS APPLICATIONS 



A.GEICULTUEE AND PHYSIOLOGY. 



BY 

JUSTUS "^LIEBIb, M.D., Ph.D., F.II.S., M.R.I.A., 

PROrBSSOR OF CHEMISTRY IN THE UNIVKRSITT Of QIESSBN, ETC., ETC 



EIHTED FROM THE MANUSCRIPT OF THE AUTHOR, 

BY LYON PLAYTAIR, Ph.D., F.G.S., 

BOKOHART MEMBER OF AND CONSULTINO CHEMIST TO THE ROYAL AORICCtTURAt 
SOCIETY OF ENGLAND, 

AM) WLUm GREGORY, M.D., F.R.S.E., 

PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF EDINBDROH 



FROM THE FOURTH LONDON EDITION, 

REVISED AND ENLARGED. 



NEW YORK : 
JOHE" WILEY, 56 WALKER STREET. 

1861. 



o 



ADVERTISEMENT 
TO THE FOURTH EDITION 



Thk present edition is enriched with a large number of recen 
analyses of manures ; and especially of the ashes of plants, 
which will be found in the Appendix to Part I. The greater 
number of these analyses have been made under the eye of the 
Author in the Laboratory at Giessen, and with the aid of the 
most improved methods. 

At the request of Professor Liebig I assisted in the preparation 
of the last edition of this Work, the various engagements of Di. 
Playfair having so fully occupied his time as to preclude him 
from giving the requisite attention to it. The same causes have 
led to my undertaking the entire revision of the present edition. 

WILLIAM GREGORY. 
UmvcRsiTY OF Edinburgh, 

March, 1847. 



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AUTHOR'S PREFACE 

TO THE THIRD EDITION. 



Many views and principles which I had endeavored to develope 
in reference to nutrition, and especially to the cultivation of 
vegetables, were strongly opposed, immediately on the appear- 
ance of the first edition of this Work. I could not, however, 
resolve to make any material change in the immediately succeed- 
ing edition, because I did not consider the scientific investigation 
of the important questions at issue as completed, and because I 
thought that I ought to trust the decision of them to experience 
alone. 

Many of the objections raised were founded upon a want of 
mutual understanding ; others related to positions and assertions 
having no connexion with the peculiar object of the book. I 
have set these aside by the omission of all passages thus called 
in question. 

In the three years which have elapsed between this edition and 
the first, I have not neglected any opportunity of subjecting to a 
rigorous and careful examination the principles which I had 
developed of the nutritive properties of plants, and their applica- 
tion to agriculture. I have endeavored to make myself acquainted 
with the condition of practical farming, and with what it requires, 
by a journey through the agricultural districts of England and 
Scotland ; and during this interval a long series of experiments 



PREFACE. 



were carried on in the Laboratory of this place, with the sole 
object of giving a firmer basis to my exposition of the causes of 
the advantageous results attending the practice of rotation of 
crops, and also of effectually banishing all doubts concerning 
their accuracy. 

In my " Chemistry in its applications to Physiology and 
Pathology," I have subjected the process of nutrition of the 
animal organism to a stricter investigation ; and I am now, for 
the first time since the completion of these labors, in a situation 
to give a simple and determinate expression to my view of the 
origin of animal excrements, and of the cause of their beneficial 
effects on the growth of all vegetables. 

Now that the conditions which render the soil productive and 
capable of affording support to plants, are ascertained, it cannot 
well be denied that from Chemistry aione further progress in 
Agriculture is to be expected. 

Every unprejudiced person will, I trust, be finally convinced 
by this third edition, that I have earnestly endeavored to perfect 
my views, and have striven, with the best intentions, to ascertain 
truth and obviate error. 

JUSTUS LIEBKi. 

GIC9SEN, 

Augiut, 1843. 



THE BRITISH ASSOCIATIOiy 



ADVANCEMENT OF SCIENCE. 



One of the most remarkable features of modern times is iha 
combination of large numbers of individuals representing the 
whole intelligence of nations, for the express purpose of ad- 
vancing science by their united efforts, of learning its progress, 
and of communicating new discoveries. The formation of such 
associations, is, in itself, an evidence that they were needed. 

It is not every one who is called by his situation in life to 
assist in extending the bounds of science ; but all mankind have 
a claim to the blessings and benefits which accrue from its 
earnest cultivation. The foundation of scientific institutions is 
an acknowledgment of these benefits, and this acknowledgment 
proceeding from whole nations may be considered the triumph of 
mind over empiricism. 

Innumerable are the aids afforded to the means of life, to 
manufactures, and to commerce, by the truths which assiduous 
and active inquirers have discovered and rendered capable of 
practical application. But it is not the mere practical utility of 
these truths which is of importance. Their influence upon 



DEDICATION. 



mental culture is most beneficial ; and the new views acquired 
by the knowledge of them enable the mind to recognise, in the 
phenomena of nature, proofs of an Infinite Wisdom, for the 
unfathomable profundity of which language has no expression. 

At one of (lie meetings of the Chemical Section of the " British 
Association for the Advancement of Science," the honorable task 
of preparing a Report upon the state of Organic Chemistry was 
imposed upon me. In the present work I present the Association 
with a part of this report. 

I have endeavored to develope, in a manner correspondent to 
the present state of science, the fundamental principles of 
Chemistry in general, and the laws of Organic Chemistry in 
particular, in their applications to Agriculture and Physiology ; 
io the causes of fermentation, decay, and putrefaction ; to the 
vinous and acetous fermentations, and to nitrification. The con- 
version of woody fibre into wood and mineral-coal, the nature of 
poisons, contagions, and miasms, and the causes of their action 
on the living organism, have been elucidated in their chemical 
relations. 

I shall be happy if I succeed in attracting the attention of men 
of science to subjects which so well merit to engage their talents 
and energies. Perfect Agriculture is the true foundation of all 
trade and industry — it is the foundation of the riches of states. 
But a rational system of Agriculture cannot be formed without 
the application of scientific principles ; for such a system must 
be based on an exact acquaintance with the means of nutrition 
of vegetables, and with the influence of soils and actions of 
manure upon them. This knowledge we must seek from Che- 
mistry, which teaches the mod3 of investigating the composition 
and of studying the characters of the different substances from 
which plants derive their nourishment. 

The chemical forces play a part in all the processes of the living 
animal organism ; and a number of transformations and changes 



DEDICATION. 



in the living body are exclusively dependent on their influence. 
The diseases incident to the period of growth of man, contagion 
and contagious matters, have their analogues in many chemical 
processes. The investigation of the chemical connexion subsist- 
ing between those actions proceeding in the living body, and the 
transformations presented by chemical compounds, has also been 
a subject of my inquiries. A perfect exhaustion of this subject, 
CO highly important to medicine, cannot be expected without the 
co-operation of physiologists. Hence I have merely brought 
forward the purely chemical part of the inquiry, and hope to 
attract attention to the subject. 

Since the time of the immortal author of the " Agricultural 
Chemistry," no chemist has occupied himself in studying the 
applications of chemical principles to the growth of vegetables, 
and to organic processes. I have endeavored to follow the path 
marked out by Sir Humphry Davy, who based his conclusions 
only on that which was capable of inquiry and proof. This is 
the path of true philosophical inquiry, which promises to lead us 
to truth — the proper object of our research. 

In presenting this Report to the British Association I feel 
myself bound to convey my sincere thanks to Dr. Lyon Play fair, 
of St. Andrew's, for the active assistance which has been afforded 
me in its preparation by that intelligent young chemist during liis 
residence in Giessen. I cannot suppress the wish that he may 
succeed in being as useful, by his profound and well-grounded 
Knowledge of chemistry, as his talents promise. 

JUSTUS LIEBIG. 

Giessen, 
Suptember 1, 1840 



CONTENTS. 



Object or the Work .....-- 1 
PART THE FIRST. 

ON THE CHEMICAL PROCESSES IN THE NUTRITION OF VEGE1ABLC9. 

CHAPTER 

I. — The Coustitueiit Elements of Plants ----- 3 

II. — The Origin and Assiniiliition of Cdrbon - - - - 5 

III. — On the Origin and Action of Humus ----- 28 

IV. — On the Assimilation of Hydrogen . .... 'do 

V. — On the Origin and Assimilation of Nitrogen - - - '^0 

VI.— On the Source of Sulphur 58 

VII. — Of the Inorganic Constituents of Plant.s . ... 64 

VIII. — On the-Formation of Arable Land ----- SI 

IX.— The Art of Culture 93 

X.— On Fallow 123 

XL— On the Rotation of Crops - 133 

XII.— On Manure - - 166 

XIII. — Retrospective view of the Preceding Theories ... 186 

Supplementary Chapters. — The Sources of Ammonia - - 205 

I.-^ Nitric Acid food for plants ? ----- 214 

Does the Nitrogen of the Air take part in Vegetation ? - 223 

Giant Sea-weed .----... 225 

Appendix to Part I. - - - - - - - - 227 

Experiments of Wiegmann and Polstorf - - - 227 

and Analyses of Boussingault - - - 231 

Analyses of Hertwig 238 

Fresenius ...-.-- 23^ 

Berth ier 240 

De Saussure ...--. 242 
Recent Analyses of the Ashes of Plants - - - 247, 254 

Analyses of Animal Excrements 255 

Urine .-...-. 256 

Guano 25S 

Marl - 264 

Ammonia in the Soil 26i 



CONTENTS. 



PART THE SECOND. 

ON THE CHEMICAL PROCESSES OF FEU MENTATION, DECAY, AND 
PUTREFACTION. 

CKAPTER PXOt 

I. — Chemical Transformations -.--.-- 265 
II. — On the Causes which etTt-t Fermentation, Dec.iy, and Putre- 
faction 26S 

III. — Fermentation and Putrf;';i"ti()n ------ 270 

IV. — On the Transformation of Bodies which do not contain Nitro- 
gen as a Constituent, ajid of those in which it is present - 280 
On the Transformaticii of Bodies containing Nitrogen - 282 
V. — Fermentation of Sugar ....... 287 

Yeast or Ferment -------- 289 

VI. — Eremacausis, or Decay ------- 295 

VII. — Eremacausis, or Decay of Bodies drstiiute of Nitrogen: 

Formation of Acetic Acid ...... 302 

VIII. — Eremacausis of Substances containing Nitrogtn. — Nitrifi- 
cation .-.------. 307 

IX. — On Vinous Fermentation : — Wine and Beer - - - 311 
X. — On Fermentation ascribed to the Growth of Fungi and of 

Infusoria ---..---- 328 

XI.— Decay of Woody Fibre 338 

XII.— Vegetable Mould 344 

XIII.— On the Mouldering of Bodies : — Paper, Brown Coal, and Mine- 
ral Coal 346 

XIV. — On Poisons, Contagions, and Miasns - - - . - 354 

Appe!vdix to Part II. - -------- 391 

Index -.---- ...... 393 



ORGANIC CHEMISTRY 



IN ITS APPLICATION TO 



*i:getable physiology and agriculture 



THk. tfojecl of Organic Chemistry is to discover the chemical 
conditions essential to the life and perfect development of animalf 
and vegetables, and generally to investigate all those processes of 
organic nature which are due to the operation of chemical laws. 
Now, the continued existence of all living beings is dependent on 
the reception by them of certain substances, which are applied 
to the nutrition of their frame. An inquiry, therefore, into the 
conditions on which the life and growth of living beings depend, 
involves the study of those nutritive substances, as well as the 
investigation of the sources whence they are derived, and of the 
changes undergone by them in the process of assimilation. 

A beautiful connexion subsists between the organic and inor- 
ganic kingdoms of nature. Inorganic matter affords food to 
plant"? ; and they, on the other hand, yield the means of subsist- 
ence to animals. The conditions necessaiy for animal and vege- 
table nutrition are essentially different. An animal requires for 
its development, and for the sustenance of its vital functions, a 
certain class of substances which can be generated only by 
organic beings possessed of life. Although many animals are 
entirely carnivorous, yet their pritnary nutriment must be derived 
from plants ; for the animals upon which they subsist receive 
their nourishment from vegetable matter. Plants, on the other 

PART I. 2 



SUBJECT OF THE WORK 



hand, find new nutritive material only in inorganic substances. 
Hence, one great end of vegetable life is to generate matter 
adapted for the nutrition of animals, out of inorganic substances, 
which are not fitted for this purpose. Now, the purport of this 
Work is, to elucidate the chemical processes engaged in the 
nutrition of vegetables, as well as the changes which they undergo 
after death. 

The first part of it will be devoted to the examination of the 
matters which supply the nutriment of plants, and of the changes 
which these matters undergo in the living organism. The che- 
mical compounds which afford to plants their principal constitu- 
ents, viz., carbon, nitrogen, hydrogen, oxygen, and sulphur, will 
here come under consideration, as well as the relations in which 
the vital functions of vegetables stand to those of the animal 
economy and to other phenomena of nature. 

The second part of the work will treat of the peculiar processes 
usually described as fermentation, putrefaction, and decay. By 
the action of these processes, the complete destruction of plants 
and animals after death is effected. Hence the changes under- 
gone by the elements of organic tissues in their t onversion into 
inorganic compounds, as well as the cause by wbic' tbp.se changes 
are determined, will become matter of inquiry. 



PART I. 



THE CHEMICAL PROCESSES IN THE NUTRITION OF 
VEGETABLES. 



CHAPTER I. 

The Constituent Element3 of Plants. 



Carbon and hydrogen invariably occur in all parts of plants. 
They form constituents of all their organs, and are essential to 
their existence. 

The substances which constitute the principal mass of every 
vegetable are compounds of carbon with oxygen and hydrogen, 
in the proper relative proportions for forming water. Woody 
fibre, starch, sugar, and gum, for example, are such compounds 
of carbon with the elements of water. In another class of sub- 
stances containing carbon as an element, oxygen and hydrogen 
are again present ; but the proportion of oxygen is greater than 
would be required for producing water by union with the hydro- 
gen. The numerous organic acids met with in plants, belong, 
with few exceptions, to this class. 

A third class of vegetable compounds contains carbon and hy- 
drogen, but no oxygen, or less of that element than would be 
required to convert all the hydrogen into water. These may be 
regarded as compounds of carbon with the elements of water, and 
an excess of hydrogen. Such are the volatile and fixed oils, 
wax, and the resins. Many of them have acid characters. 

The juices of all vegetables contain organic acids, generally 
combined with the inorganic bases, or metallic oxides ; for metal- 
lic oxides exist in every plant, and may be detected in its ashes 
after incineration. 



THE CONSTITUENT ELEMENTS OF PLANTS. 



Nitrogen is found in plants in the form of vegetable albumen 
and gluten ; it is also a constituent of some of the acids, and of 
what are termed the " indifferent substances " of plants, as well 
as of those peculiar vegetable compounds called " organic 
bases," which possess all the properties of metallic oxides. The 
seeds also of all plants contain nitrogenous compounds. 

Estimated by its proportional weight, nitrogen forms only a 
small part of plants ; but it is never entirely absent from any 
part of them. Even when it does not absolutely enter into the 
composition of a particular part or organ, it is always to be found 
in the fluids which pervade it. 

The nitrogenous compounds thus invariably present in the 
seeds and juices of plants contain a certain quantity of sulphur. 
When the juices, seeds, or organs of particular kinds of plants 
are subjected to distillation along with water, peculiar oily sub- 
stances pass over. These are volatile, and are characterized by 
their large proportion, both of sulphur arid of nitrogen. The 
volatile oils of the horse-radish and of mustard are examples of 
this class of bodies. 

From the remarics now made, it is obvious that there are two 
great classes into which all vegetable products may be arranged. 
The first of these contains nitrogen ; in the last this element is 
absent. The compounds destitute of nitrogen may be divided 
into those in which oxygen forms a constituent (starch, lignine, 
iSic), and those into which it does not enter (oils of turpentine 
and lemon, &c.). The nitrogenous compounds may, in like 
manner, be divided into three smaller classes. The first of these 
is distinguished by containing both sulphur and oxygen (in all 
seeds) ; the second contains sulphur, but is devoid of oxygen (as 
oil of mustard) ; while the third is composed of bodies from 
which sulphur is entirely absent (organic bases). 

It follows from the facts thus far detailed, that the development 
of a plant requires the presence, first, of substances containing 
carbon, nitrogen, and sulphur, and capable of yielding these 
elements to the growing organism ; secondly, of water and its 
elements ; and lastly, of a soil to furnish the inorganic matters 
which are likewise essential to vegetable life. 



PROPERTIES OF HUMUS. 



CHAPTER II. 
THE ORIGIN AND ASSIMII-ATION OF CARBON. 

Composition of Humus. 

Some virgin soils, such as those of America, contain vegetable 
matter in large proportion ; and as these have been found emi- 
nently adapted for the cultivation of most plants, the organic 
matter contained in them has naturally been recognised as the 
cause of their fertility.* To this matter, the term " vegetable 
mould " or humus has been applied. Indeed, this peculiar sub- 
stance appears to play such an important part in the phenomena 
of vegetation, that vegetable physiologists have been induced to 
ascribe the fertility of every soil to its presence. It is believed 
by many to be the principal nutriment of plants, and is supposed 
to be extracted by them from the soil in which they grow. It 
is a product of the putrefaction and decay of vegetable matter. 

The humus, to which allusion has been made, is described by 
chemists as a brown substance easily soluble in alkalies, but only 
slightly so in water, and produced during the decomposition of 
vegetable matters by the action of acids or alkalies. It has, 
however, received various names, according to the different ex- 
ternal characters and chemical properties which it presents. 
Thus, uJmin, humic acid, coal of humus, and humin, are names 

* When the weight of the soluble parts of this vegetable matter is com- 
pared with that of the plants growing upon t, it is seen that only a very 
small part of their substance could have been procured through its agency. 
This is the case even in the most fertile soils. — (Saussure, Richerchei 
tiir la V6g(tation. 



OF THE ASSIMILATION OF CARBON. 



applied to modifications of humus. They are obtained by treat- 
ing peat, woody fibre, soot, or brown coal, with alkalies ; by de- 
composing sugar, starch, or sugar of milk by means of acids ; or 
by exposing alkaline solutions of tannic and gallic acids to the 
action of the air. 

The modifications of humus which are soluble in alkalies, are 
called humic acid ; while those which are insoluble have received 
/he designations of humin and coal of humus. 

The names given to these substances might cause it to be sup- 
posed that their composition is identical. But a more erroneous 
notion could not be entertained ; since even sugar, acetic acid, 
and resin, do not differ more widely in the proportions of their 
constituent elements, than do the various modifications of humus. 

Humic acid formed by the action of hydrate of potash upon 
sawdust contains, according to the accurate analysis of Peligot, 
72 per cent, of carbon, while the humic acid obtained from turf 
and brown coal contains, according to Sprengel, only 58 per 
cent. ; that produced by the action of dilute sulphuric acid upon 
sugar, 57 per cent, according to Malaguti ; and that, lastly, 
which is obtained from sugar or from starch, by means of muri- 
atic acid, according to the analysis of Stein, 64 per cent. Mala- 
guti states, moreover, that humic acid contains an equal number 
of equivalents of oxygen and hydrogen, that is to say, that these 
elements exist in it in the proportions for forming water ; while, 
according to Sprengel, the oxygen is in excess ; and Peligot esti- 
mates the quantity of hydrogen at 14 equivalents, and the oxygen 
at only 6 equivalents, making the deficiency of oxygen as great 
as 8 equivalents. Mulder and Herrmann have shown that de- 
cayed willow- wood, peat, or vegetable mould, after being treat- 
ed with water and alcohol, leave a solid brown substance, which 
yields to alkalies a peculiar humic acid. This humic acid con- 
sists of carbon and the elements of water. But besides these 
usual constituents, it contains a certain quantity of ammonia, in 
a state of cliemical combination. 

It is quite evident, therefore, that chemists have been in the 
habit of designating by the names of humic acid or humin, all 
the brown or black-colored products of the decomposition of 
organic bodies, according as they were soluble or insoluble in 



PROPERTIES OF HUMUS. 



alkalies ; although in their composition and mode of origin the 
substances thus confounded might be in no way allied. 

Not the slightest ground exists for the belief that one or other 
of these artificial products of the decomposition of vegetable 
matters exists in nature, in the form, and endowed with the 
properties, of the vegetable constituents of mould ; there is not 
the shadow of a proof that one of them exerts any influence on 
the growth of plants, either in the way of nourishment or other- 
wise. 

Vegetable physiologists have, without any apparent reason, im- 
puted the known properties of the humus and humic acids of che- 
mists to that constituent of mould which has received the same 
name, and in this way have been led to their theoretical notions 
respecting the functions of the latter substance in vegetation. 

The opinion that the substance called humus is extracted from 
the soil by the roots of plants, and that the carbon entering into 
its composition serves to nourish their tissues, without previously 
assuming another form, is considered by many as so firmly estab- 
lished that any evidence in its favor has been deemed unneces- 
sary : the obvious difference in the growth of plants according to 
the known abundance or scarcity of humus in the soil, seemed 
to afford incontestable proof of its correctness.* 

Yet, this position, when submitted to a strict examination, is 
found to be untenable, and it becomes evident from most con- 
clusive proofs, that humus in the form in which it exists in 
THE SOIL, does not yield the smallest nourishment to plants. 

The adherence to the above incorrect opinion has hitherto ren- 
dered it impossible to ascertain the true theory of the nutritive 
process in vegetables, and has thus deprived us of our best guide 
to a rational practice in agriculture. Any great improvement 
in that most important of all arts is inconceivable, without a 
deeper and more perfect acquaintance with the substances which 
nourish plants, and with the sources whence they are derived ; 
and no other cause can be discovered to account for the fluctuat- 

* This remark applies more to German than to English botanists and 
physiologists. In England, the idea that humus, as such, affords nourish- 
ment to plants is by no means general ; but on the Continent, the viewi 
of Berzelius on this subject have been almost universally adopted. — Ed. 



OF THE ASSIMILATION OF CARBON. 



ing and uncertain state of our knowledge on this subject up to 
the present time, than that modern physiology has not kept pace 
with the rapid progress of chemistry. 

In the following inquiry we shall suppose the humus of vege- 
table physiologists to be really endowed with the properties 
recognised by chemists in the brownish-black deposits obtained 
by precipitating an alkaline decoction of mould or peat by means 
of acids, and which they name humic acid. 

HuMic ACID, when first precipitated, is a flocculent substance, 
is soluble in 2500 times its weight of water, and combines with 
alkalies, forming with lime and magnesia compounds of the same 
degree of solubility (Sprengel). 

Vegetable physiologists agree in the supposition that by the 
aid of water humus is rendered capable of being absorbed by the 
roots of plants. But according to the observation of chemists, 
humic acid is soluble only when newly precipitated, and becomes 
completely insoluble when dried in the air, or when exposed in 
the moist state to the freezing temperature (Sprengel). 

Both the cold of winter and the heat of summer, therefore, 
are destructive of the solubility of humic acid, and at the same 
time of its capability of being assimilated by plants. So that, 
if it is absorbed by plants, it must be in some altered form. 

The correctness of these observations is easily demonstrated 
by treating a portion of good mould with cold water. The fluid 
remains colorless, and is found to have dissolved less than 
TToVto" P^^'' of its weight of organic matters, and to contain 
merely the salts which are present in rain-water. 

Decayed oak-wood, likewise, of which humic acid is the prin- 
cipal constituent, was found by Berzelius to yield to cold water 
only slight traces of soluble materials ; and I have myself veri- 
fied this observation on the decayed wood of beech and fir. 

These facts, which show that humic acid, in its insoluble con- 
dition, cannot serve for the nourishment of plants, have not 
escaped the notice of physiologists ; and hence they have 
assumed that the lime or the different alkalies found in the ashes 
of vegetables, render soluble the hujTiic acid, and fit it for the 
orocess of assimilation. 

Alkalies and alkaline earths do exist in the different kinds of 



ABSORPTION OF HUMUS. 



ioil, in sufficient quantity to form such soluble compounds with 
lumic acid. 

Now, let us suppose that humic acid is absorbed by plants in 

ihe form of that salt which contains the largest proportion of 

lumic acid, namely, in the form of humate of lime ; and then, 

from the known quantity of the alkaline bases contained in the 

ishes of plants, let us calculate the amount of humic acid which 

might be assimilated in this manner. Let us admit, likewise, 

chat potash, soda, and the oxides of iron and manganese have the 

?ame capacity of saturation as lime with respect to humic acid, 

md then we may take as the basis of our calculation the analysis 

if M. Berthier, who found that 1000 lbs. of dry fir-wood yielded 

••I-3 lbs. of ashes, and that in every 100 lbs. of these ashes, 

educting the chloride of potassium, the silicate, and sulphate 

f potash, 46-1 lbs. consisted of the basic metallic oxides, potash, 

toda, lime, magnesia, iron, and manganese. 

One Hessian acre* of woodland yields annually, according to 
1 )r. Heyer, on an average, 2650 lbs. of dry fir-wood, which con 
lains 10*07 lbs. of metallic oxides. 

Now, according to the estimates of Malaguti and Sprengel, 1 
io. of lime combines chemically with 10-9 lbs. of humic acid ; 
1 0-07 lbs. of the metallic oxides would accordingly introduce 
i.ito the trees nearly 111 lbs. of humic acid, which, admitting 
numic acid to contain 58 per cent, of carbon, would correspond 
lo 165 lbs. of dry wood. But we have seen that 2650 lbs. of 
(ir-wood are really produced. 

Again, if the quantity of humic acid which might be intro- 
luced into wheat in the form of humates, is calculated from the 
Known proportion of metallic oxides existing in wheat straw (the 
sulphates and chlorides also contained in the ashes of the straw 
not being included), it will be found that the wheat growing on 
one Hessian acre would receive in. that way 57^ lbs. of humic 
acid, corresponding to 85 lbs. of woody fibre. But the extent 
of land just mentioned produces, independently of the roots and 
grain, 1780 lbs. of straw, the composition of which is the same 
as thai of woody fibre. 

* One Hessian acre is equal to 40,000 square feet, Hessian, or 26,911 
■quare feet, English measure. 
PART TI. 2* 



10 OF THE ASSIMILATION OF CARBON. 

It has been taken for granted in these calculations, that the 
basic metallic oxides which have served to introduce humic acid 
into the plants do not return to the soil, since it is certain thai 
they remain fixed in the parts newly formed during the process 
of growth. 

Let us now calculate the quantity of humic acid which plants 
can receive under the most favorable circumstances, viz., through 
the agency of rain-water. 

The quantity of rain which falls at Erfurt, one of the most 
fertile districts of Germany, during the months of April, May, 
June, and July, is stated by Schubler to be 17^ lbs. over every 
Hessian square foot of surface (=0-672 square foot English) : 
one Hessian acre, or 26,910 square feet, consequently receive, 
in round numbers, 700,000 lbs. of rain-water. 

If, now, we suppose that the whole quantity of this rain is 
taken up by the roots of a summer plant, which ripens four 
months after it is planted, so that not a pound of water evaporates 
except from the leaves of the plant ; and if we further assume 
that the water thus absorbed is saturated with humate of lime 
(the most generally diffused of the humates, and that which con- 
tains the largest proportion of humic acid) ; then the plants thus 
nourished would not receive more than 350 lbs. of humic acid, 
since one part of humate of lime requires 2000 parts of water 
for solution. 

But the extent of land which we have mentioned produces 
2580 lbs. of corn (in grain and straw, the roots not included), 
or 20,000 lbs. of beet-root (without the leaves and small fibres 
of the radicle). It is quite evident that the 350 lbs. of humic 
acid, supposed to be absorbed, cannot account even for the 
quantity of carbon contained in the fibres of the radicle and 
leaves alone, even if the supposition were correct, that the whole 
of the rain-water was absorbed by the plants. But since it is 
known that only a small portion of V.he rain-water which falls 
upon the surface of the earth is absorbed by plants and evapo- 
rates through their leaves, the quantity of carbon which can be 
conveyed into tbem in any conceivable manner, by means of 
huinic acid, must be almost inappreciable, in comuarison with 
.hat actually produced in vegetation. 



ABSORPTION OF HUMUS. 11 

Other considerations of a higher nature confute the common 
view respecting the nutritive office of humic acid, in a manner 
so clear and conclusive that it is difficult to conceive how it 
could have been so generally adopted. 

Fertile land produces carbon in the form of wood, hay, grain, 
and other kinds of gi'owth, the masses of which differ in a re- 
markable degree. 

2650 lbs. of firs, pines, beeches, &c., grow annually as wood 
upon one Hessian acre of forest-land with an average soil. The 
same superficies yields 2500 lbs. of hay. 

A similar surface of corn-land gives from 18,000 to 20,000 
lbs. of beet-root ; or 800 lbs. of rye, and 1780 lbs. of straw, — in 
all 2580 lbs. 

One hundred parts of dry fir- wood contain 38 parts of carbon ; 
therefoi'e, 2650 lbs. contain 1007 lbs. of carbon. 

One hundred parts of hay,* dried in air, contain 40-73 parts 
carbon. Accordingly, 2500 lbs. of hay contain 1018 lbs. of 
carbon. 

Beet-roots contain from 89 to 89-5 parts water, and from 10-5 
to 11 parts solid matter, which contains 40 per cent, of carbon. f 

20,000 lbs. of beet-root contain, therefore, 880 lbs. of carbon, 
the quantity of this element in the leaves and small roots not 
being included in the calculation. 

One hundred parts of straw,:}: dried in air, contain 38 per cent, 
of carbon ; therefore, 1780 lbs. of straw contain 676 lbs. of 
carbon. One hundred parts of corn contain 43 parts of carbon ; 
800 lbs. must therefore contain 344 lbs. ; in all 1020 lbs. of 
carbon. 

* 100 parts of hay, dried at 100° C. (212" F.) and burned with oxide of 
copper in a stream of oxygen gas, yielded 5r93 water, 166 8 caibonic acid, 
and 6'82 of ashes. This gives 45'87 carbon, 5"76 hydrogen. 41*55 oxygen, 
and 6 82 ashes. Hay, dried in the air, loses 11"'2 p. c. water at 100" C. 
(212° F.)— Dr. Will. 

f I. 0'8075 of dry beet gave 0-416 water and I'lSS carbonic acid. II 
0"400 gave 0201 water, and 0'505 carbonic acid. — Dr. Will. 

X straw analysed in the same manner, and dried at 100° C, gave 46'37 
p. c. of carbon, 5"68 p. c. of hydrogen, 43"93 p. c. of oxygen and 4"02 p. c. 
of ashes. Straw dried in the air at 100° C. lost 18 p. c. of water — Da, 
Will. 



12 OF THE ASSIMILATION OF CARBON. 

26,910 square feet of wood-land produce of carbon . . 1007 lbs. 

" " meadow-land " . . 1018 lbs. 

" " arable-land, beet-roots without leaves SSO lbs. 

corn . .... 1020 lbs. 

It must be concluded from these incontestable facts, that equal 
surfaces of cultivated land of an average fertility are capable 
of producing equal quantities of carbon ; yet, how unlike have 
been the different conditions of the growth of the plants from 
which this has been deduced ! 

Let us now inquire whence the grass in a meadow, or the 
wood in a forest, receives its carbon, since there, carbon has not 
been given to it as nourishment ? and how it happens, that the 
soil, thus exhausted, instead of becoming poorer, becomes every 
year richer in this element ? 

A certain quantity of carbon is taken every year from the 
forest or meadow, in the form of wood or hay, and, in spite 
of this, the quantity of carbon in the soil augments ; it become'^ 
richer in humus. 

It is said that in fields and orchards all the carbon which may 
have been taken away as leaves, as straw, as seeds, or as fruit, 
is replaced by means of manure ; and yet this soil produces na 
more carbon than that of the forest or meadow, where it is nevei 
replaced. It cannot be conceived that the laws for the nutrition 
of plants are changed by culture, — that the sources of carbon 
for fruit or grain, and for grass or trees, in meadows and forests, 
are different. 

It is not denied that manure exercises an influence upon the 
development of plants ; but it may be affirmed with positive cer- 
tainty, that to its carbon is not due the favorable influence which 
it exercises, because we find that the quantity of carbon produced 
by manured lands is not greater than that yielded by lands which 
are not manured. The discussion as to the manner in which 
manure acts has nothing to do with the present question, — which 
is, the origin of the carbon. The carbon must be derived from 
other sources ; and as the soil does not yield it, it can only be 
extracted from the atmosphere. 

In attempting to explain the origin of carbon in plants, it has 
never been considered that the question is intimately connected 



FERTILITY OF DIFFERENT SOILS. 13 

with that of the origin of humus. It is universally admitted 
that humus arises from the decay of plants. No primitive 
humus, therefore, can have existed-^for plants must have pre 
ceded the humus. 

Now, whence did the first vegetables derive their carbon ? and 
in what form is the carbon contained in the atmosphere ? 

These two questions involve the consideration of two most 
remarkable natural phenomena, which, by their reciprocal and 
uninterrupted influence, maintain the life of individual animals 
and vegetables, and the continued existence of both kingdoms of 
organic nature. 

One of these questions is connected with the invariable con- 
dition of the air with respect to oxygen. One hundred volumes 
of air have been found, at every period and in every climate, to 
contain 21 volumes of oxygen, with such small deviations that 
tliey must be ascribed to errors of observation. 

Although the absolute quantity of oxygen contained in the 
atmosphere appears very great when represented by numbers^ 
yet it is not inexhaustible. One man consumes by respiration 
25 cubic feet of oxygen in 24 hours; 10 cwt. of charcoal con 
sume 32,066 cubic feet of oxygen during its combustion, so that 
a single iron furnace consumes annually hundreds of millions of 
cubic feet ; and a small town like Giessen (with about 7000 in- 
habitants) exacts yearly from the air, by the wood employed as 
fuel, more than 551 millions of cubic feet of this gas. 

When we consider facts such as these, our former statement, 
that the quantity of oxygen in the atmosphere does not diminish 
in the course of ages* — that the air at the present day, for exam- 

* If the atmosphere possessed, in its whole extent, the same density as it 
does on the surface of the sea, it would have a height of 24,555 Parisian 
feet; but it contains the vapor of water, so that we may assume its heiglit 
to be one geographical mile=;2'2,843 Parisian feet. Tfow, the radius of the 
earth is equal to 860 geographical miles ; hence the 

Volume of the atmosphere=9,307,500 cubic miles. 
Volume of oxygen . . =1,954,578 " 
Volume of carbonic acid =3,862"7 '* 

A man daily consumes 45,000 cubic inches (Parisian) of oxygen A man 



14 OF THE ASSIMILATION OF CARBON. 

pie, does not contain less oxygen than that found in jars buried for 
1800 years in Pompeii — appears quite incomprehensible, unless 
some cause exists capable of replacing the oxygen abstracted. 
EIow does it happen, then, that the proportion of oxygen in the 
atmosphere is thus invariable ? 

The answer to this question depends upon another, namely 
what becomes of the carbonic acid produced during the respira- 
tion of animals, and by the process of combustion ? A cubic 
foot of oxygen gas, by uniting with carbon so as to form carbonic 
acid, does not change its volume. The billions of cubic feet of 
oxygen extracted from the atmosphere, are immediately supplied 
by the same number of billions of cubic feet of carbonic acid. 

The most exact and trustworthy experiments of De Saussure, 
made in every season for a space of three years, have shown 
that the air contains on an average 0'000415 of its own volume 
of carbonic acid gas ; so that, allowing for the inaccuracies of the 
experiments, which must diminish the quantity obtained, the pro- 
portion of carbonic acid in the atmosphere may be legarded as 
nearly equal to toVo' P^^'^ of its weight. The quantity varies 
according to the seasons ; but the yearly average remains cor- 
tinually the same. 

We have reason to believe that this proportion was much 
greater in past ages ; and nevertheless, the immense masses of 
carbonic acid which annually flow into the atmosphere from sc 
many causes, ought perceptibly to increase its quantity from year 
to year. But we find that all earlier observers describe its 

yearly consumes 9505"2 cubic feet. 1000 million men yearly consume 
9,505,200,000,000 cubic feet (Parisian). 

Without exaggeration we may suppose that double this quantity is con- 
fiumed in the support of respiration of the lower animals, and in the pro- 
cesses of decay and combustion. From this it follows, that the annual con- 
sumption of oxygen amounts to 2'392355 cubic miles, or in round numbers 
to 2'4 cubic miles Thus, every trace of oxygen would be removed from 
the atmosphere in 800,000 years. But it would be rendered quite unfit for 
the support either of respiration or combustion in a much shorter time. 
When the quantity of oxygen in the air is diminished 8 per cent., and the 
oxygen thus abstracted is replaced by its own volume of carbonic acid, the 
'alter exerts a fatal action upon animal life, and extinguishes tlie combus- 
tion of a burning body. 



QUANTITY OF OXYGEN IN THE ATMOSPHERE. 15 

volume as from one-half to ten times greater than that which it 
nas at the present time : so that we can hence at most conclude 
that it has diminished. 

It is quite evident that the invariable quantities of carbonic acid 
and oxygen in the atmosphere, must stand in some fixed relation 
to one another ; a cause must exist which prevents the increase 
of carbonic acid by removing that which is constantly forming ; 
and there must be some means of replacing the oxygen removed 
from the air by the processes of combustion and putrefaction, as 
well as by the respiration of animals. 

Both these causes are united in the process of vegetable life. 

The facts which we have stated in the preceding pages prove 
that the carbon of plants must be derived exclusively from the 
atmosphere. Now, carbon exists in the atmosphere only in the 
form of carbonic acid, and therefore in a state of combination 
with oxygen. 

It has been already mentioned, that carbon and the elements of 
water form the principal constituents of vegetables ; the quantity 
of the substances which do not possess this composition being in 
a very small proportion. Now, the relative quantity of oxygen 
in the whole mass is less than in carbonic acid ; for the latter 
contains two equivalents of oxygen, whilst one only is required 
to unite with hydrogen in the proportion to form water. The 
vegetable products containing oxygen in larger proportion than 
this, are, comparatively, few in number ; indeed, in many the 
hydrogen is in great excess. It is obvious, that when the hydro- 
gen of water is assimilated by a plant, the oxygen in combination 
with it must be liberated, and will afford a quantity of this ele- 
ment sufficient for the wants of the plant. If this be the case, 
the oxygen contained in the carbonic acid is quite unnecessary in 
the process of vegetable nutrition, and it will consequently escape 
into the atmosphere in a gaseous form. It is therefore certain, 
that plants must possess the power of decomposing carbonic acid, 
since they appropriate its carbon for their own use. The forma- 
tion of their principal component substances must necessarily be 
attended with the separation of the carbon of the carbonic acid 
from the oxygen, which must be returned to the atmosphere, 
tvhilst the carbon enters into combination with water or its ele- 



18 OF THE ASSIMILATION OF CARBON. 

ments. The atmosphere must thus receive a volume of oxygen 
for every volume of carbonic acid, the carbon of which has be. 
come a constituent of the plant. 

This remarkable property of plants has been demonstrated in 
the most certain manner, and it is in the power of every person 
to convince himself of its existence. The leaves aiid other green 
parts of a plant absorb carbonic acid, and emit an equal volume 
of oxygen. They possess this property quite independently of 
the plant ; for, if after being separated from the stem, they are 
placed in water containing carbonic acid, and exposed in that 
condition to the sun's light, the carbonic acid is, after a time, 
found to have disappeared entirely from the water. If the ex- 
periment is conducted under a glass receiver filled with water, 
the oxygen emitted from the plant may be collected and examined. 
When no more oxygen gas is. evolved, it is a sign that all the 
dissolved carbonic acid is decomposed ; but the operation recom- 
mences if a new portion of it is added. 

Plants do not emit gas when placed in water either free from 
carbonic acid, or containing an alkali that protects it from assi- 
milation. 

These observations were first made by Priestley and Senne- 
bier. The excellent experiments of De Saussure have further 
shown, that plants increase in weight during the decomposition 
of carbonic acid and separation of oxygen. This increase in 
weight is greater than can be accounted for by the quantity of 
carbon assimilated ; a fact which confirms the view, that the ele- 
ments of water are assimilated at the same time. 

The life of plants is closely connected with that of animals, in 
a most simple manner, and for a wise and sublime purpose. 

The presence of a rich and luxuriant vegetation may be con. 
ceived without the concurrence of animal life, but the existence 
of animals is undoubtedly dependent upon the life and develop- 
ment of plants. 

Plants not only afford the means of nutrition for the growth 
and continuance of animal organization, but they likewise furnish 
that which is essential for the support of the important vital pro- 
cess of respiration ; for, besides separating all noxious matters 
from the atmosphere, they are an inexhaustible source of pure 



ITS SOURCE THE ATMOSPHERE. 17 

oxygen, and they thus supply to the air the loss constantly sus- 
tained by it. Animals, on the other hand, expire carbon, while 
plants inspire it ; and thus the composition of the atmosphere, 
the medium in which both exist, is maintained constantly un- 
changed. 

It may be asked — Is the quantity of carbonic acid in the atmo- 
sphere, scarcely amounting to 1-lOth per cent., sufficient for the 
wants of the whole vegetation on the surface of the earth, — is it 
possible that the carbon of plants has its origin from the air alone ? 
This question is very easily answered. It is known that a 
column of air of 1427 lbs. weight rests upon every square Hes- 
sian foot (=0-567 square foot English) of the surface of the 
earth ; the diameter of the earth and its superficies are likewise 
known, so that the weight of the atmosphere can be calculated 
with the greatest exactness. The thousandth-part of this is car- 
bonic acid, which contains upwards of 27 per cent, carbon. By 
this calculation it can be shown, that the atmosphere contains 
3085 billion lbs. of carbon — a quantity which amounts to more 
than the weight of all the plants, and of all the strata of mineral 
and brown coal existing on the earth. This carbon is, therefore, 
more than adequate to supply all the purposes for which it is re- 
quired. The quantity of carbon contained in sea-water is pro- 
portionally still greater. 

If, for the sake of argument, we suppose the superficies of the 
leaves and other green parts of plants, by which the absorption 
of carbonic acid is effected, to be double that of the soil upon 
which they grow — a supposition much under the truth in the 
case of woods, meadows, and corn-fields — let us further sup- 
pose, that from a stratum of air two feet thick, resting on an acre 
(Hessian) of land, that is, from 80,000 cubic feet (Hessian) of 
air, there is absorbed in every second of time, for eight hours 
daily, carbonic acid equal to 0.00067 of the volume of the air, 
or 7oVo"th of its weight ; then those leaves would receive above 
1000 lbs. of carbon in 200 days.* 

* The quantity of carbonic acid which can be extracted from the air in 
a given time, is shown by the following calculation. During the white- 
washing of a small chamber, the fiuperficies of the walls and roof of which 
Vre will suppose to be 105 square metres, and which receives six coats of 



18 OF TH2 ASSIMILATION OF CARBON. 

But it is inconceivable, that the functions of the organs of a 
plant can cease for any one monaent during its life, as long as 
those organs are not exposed to the action of a process which 
may counteract the performance of their proper functions. The 
roots and other parts of it, possessing the same property, con- 
stantly absorb water and carbonic acid. This power is inde- 
pendent of solar light. During the night, carbonic acid is accu- 
mulated in all parts of their structure ; and the decomposition of 
the carbonic acid, the assimilation of the carbon, and the exha- 
lation of oxygen, commence from the instant that the rays of the 
sun strike them. As soon as a young plant breaks through the 
surface of the ground, it begins to acquire color from the top 
downwards ; and the true formation of woody tissue commences 
at the same time. 

The atmosphere is constantly in motion, both horizontally and 
vertically. The same spot is alternately supplied with air pro- 
ceeding from the poles or from the equator. A gentle breeze 
moves in an hour over six German miles, and in less than eight 
days over the distance between us and the tropics or the poles. 
When the vegetable kingdom in the temperate and cold zones 
ceases to decompose the carbonic acid generated by the processes 
of respiration and combustion, the proper, constant, and inex- 
haustible sources of oxygen gas are the tropics and warm cli- 
mates, where a sky seldom clouded permits the glowing rays of 
the sun to shine upon an immeasurably luxuriant vegetation. In 

lime in four days, carbonic acid is extracted from the air, and the lime is 
consequently converted, on the surface, into a carbonate. It has been ac- 
curately determined that one square decimetre receives in this way a coat- 
ing of carbonate of lime weighing 0'732 grammes. Upon the 105 square 
metres already mentioned there must accordingly be formed 76SG grammes 
of carbonate of lime, which contain 432 )'6 grammes of carbonic acid. 
The weight of one cubic decimetre of carbonic acid being calculated at 
two grammes (more accurately 1"9797S), the above-mentioned surface must 
absorb in four days 2*193 cubic metres of carbonic acid. 2500 square me- 
tres (one Hessian acre) would absorb, under a similar treatment, 51^ cubic 
metres = ISIS cubic feet of carbonic acid in four days. In 200 days it 
would absorb 2575 cubic metres = 904,401 cubic feet, which contain 
11,353 lbs. of carbonic acid, of which 3304 lbs. are carbon, a quantity three 
times as great as that which is assimilated by the leaves and roots growing- 
upon the same space. 



ITS SOURCE THE ATMOSPHERE. 18 

our winter, when artificial warmth must replace deficient heat 
of the sun, carbonic acid is produced in superabundance, and is 
expended in the nourishment of tropical plants. The great 
stream of air, which is occasioned by the heating of the equator- 
ial regions and by the revolution of the eart}!, carries with it in 
its passage to the equator the carbonic acid generated during our 
winters ; and, in its return to the polar regions, brings with it the 
oxygen produced by the tropical vegetation. 

The experiments of De Saussure have proved, that the uppei 
strata of the air contain more carbonic acid than the lower, which 
are in contact with plants ; and that the quantity is greater by 
night, than by day, when it undei'goes decomposition. 

Plants thus improve the air, by the removal of carbonic acid, 
and by the renewal of oxygen, which is immediately applied to 
the use of man and animals. The horizontal currents of the 
atmosphere bring with them as much as they carry away, and 
the interchange of air between the upper and lower strata, caused 
by their difference of temperature, is extremely trifling when 
compared with the horizontal movements of the winds. Thus 
vegetable culture heightens the healthy state of a country, so 
that a previously healthy country would be rendered quite unin- 
habitable by the cessation of all cultivation. 

The various layers of wood and mineral coal, as well as peat, 
form the remains of a primeval vegetation. The carbon con- 
tained in them must have been originally in the atmosphere as 
carbonic acid, in which form it was assimilated by the plants 
which constitute these formations. It follows from this, that the 
atmosphere must be richer in oxygen at the present time than in 
former periods of the earth's history. The increase must be 
exactly equal in volume to the carbonic acid abstracted in the 
nourishment of a former vegetation, and must, therefore, corres- 
pond to the quantity of carbon and hydrogen contained in the 
carboniferous deposit. Thus, by the deposition of ten cubic feet 
Hessian (5-51 cubic feet English) of Newcastle splint coal (of 
the formula Cj 4H1 3O, and specific gravity 1228), the atmosphere 
must have been deprived of above eighteen thousand cubic feet 
Hessian (9918 cubic feet English) of caroonic acid, and must 
'iiave been enriched with the same quantity of oxygen. A further 



20 OF THE ASSIMILATION OF CARBON 

quantity of oxygen amounting to 4480 cubic feet Hessian (2468 
English) must have been furnished to the air by the decomposi- 
tion of water, for 10 cubic feel Hessian of coal contains hydro- 
gen corresponding to this amount. In former ages, therefore, the 
atmosphere must have contained less oxygen, but a much larger 
proportion of carbonic acid, than it does at the present time ; a 
circumstance which accounts for the richness and luxuriance of 
the earlier vegetation. When this became entombed, the condi- 
tions were established, under which higher forms of animal life 
were capable of existing. (Brogniart.) 

But a certain period must have arrived in which the quantity 
of carbonic acid contained in the air experienced neither increase 
nor diminution in any appreciable quantity. For if it received 
an additional quantity to its usual proportion, an increased vege- 
tation would be the natural consequence, and the excess would 
thus be speedily removed. And, on the other hand, if the gas was 
less than the normal quantity, the progress of vegetation would 
be retarded, and the proportion would soon attain its proper stand- 
ard. When man appeared on the earth, the air was rendered 
constant in its composition. 

The most important function in the life of plants, or, in other 
words, in their assimilation of carbon, is the separation, we 
might almost say the generation, of oxygen. No matter can be 
considered as nutritious, or as necessary to the growth of plants^ 
which possesses a composition either similar to or identical with 
theirs ; because the assimilation of such a substance could be 
effected without the exercise of this function. The reverse is 
the case in the nutrition of animals. Hence such substances, 
as sugar, starch, and gum, themselves the products of plants, 
cannot be adapted for assimilation. And this is rendered certain 
by the experiments of vegetable physiologists, who have shown 
that aqueous solutions of these bodies are imbibed by the roots of 
plants, and carried to all parts of their structure, but are not 
assimilated ; they cannot, thei'efore, be employed in their nutrition. 

In the second part of the work we shall adduce satisfactory 
proofs that decayed woody fibre (hu7nus) contains carbon and the 
elements of water, without an excess of oxygen ; its composition 



SEPARATION OF OXYGEN. 31 

(in 100 parts) differing from that of woody fibre only in its being 
richer in carbon. 

Misled by this simplicity in its constitution, physiologists found 
no difficulty in discovering the mode of the formation of woody 
fibre ; for they say,* humus has only to enter into combination 
with water, in order to effect the formation of woody fibre, and 
other substances similarly composed, such as sugar, starch, and 
gum. But they forget that their own experiments have suffi- 
ciently demonstrated the inaptitude of these substances for assimi- 
lation. Yet we could scarcely conceive a form more fitted for 
assimilation than that of the substances just mentioned. They 
contain all the elements of woody fibre, and with respect to 
their composition in 100 parts, they correspond closely with 
humus ; but they do not nourish plants. 

All the erroneous opinions concerning the modus operandi of 
humus have their origin in the false notions entertained respect- 
ing the most important vital functions of plants ; analogy, that 
fertile source of error, having, unfortunately, led to the very 
unapt comparison of the vital functions of plants with those of 
animals. 

Substances, such as sugar, starch, &c., containing carbon and 
the elements of water, are products of the life of plants which 
live only whilst they generate them. The same may be said of 
humus, for it can be formed in plants like the former substances. 
Smithson, Jameson, and Thomson, found that the black excre- 
tions of unhealthy elms, oaks, and horse-chestnuts, consisted of 
humic acid in combination with alkalies. Berzelius detected 
similar products in the bark of most trees. Now, can it be sup- 
posed that the diseased organs of a plant possess the power of 
generating the matter to which its sustenance and vigor are 
ascribed ? 

How does it happen, it may be asked, that the absorption of 
carbon from the atmosphere by plants is doubted by many bota- 
nists and vegetable physiologists, and that by the greater number 
;he purification of the air by means of them is wholly denied ? 

These doubts have arisen from an erroneous consideration of 

• Meyen, Pflanzenphysiolcgie, II., S. 141, 



22 OF THE ASSIMILATION OF CARBON. 

the behavior of plants during the night. The experiments of 
Ingenhouss were in a great degree the cause of the uncertainty 
of opinion regarding the influence of plants in purifying the air. 
His observation that green plants emit carbonic acid in the dark, 
led De Saussure and Grischow to new investigations, by which 
they ascertained that under such conditions plants do really 
absorb oxygen and emit carbonic acid ; but that the whole volume 
of air undergoes diminution at the same time. From the latter 
fact it follows, that the quantity of oxygen gas absorbed is greater 
than the volume of carbonic acid separated; for, if both Avere 
equal, no diminution could occur. These facts cannot be do'ubt- 
ed, but the views based on them have been so false, that nothing, 
except the total disregard and the utmost ignorance of the chemi- 
cal relations of plants to the atmosphere, can account for their 
adoption. 

It is known that nitrogen, hydrogen, and a number of other 
gases, exercise a peculiar, and, in general, an injurious influence 
upon living plants. Is it, then, probable, that oxygen, one of the 
most energetic agents in nature, should remain without influence 
on plants when one of their peculiar processes of assimilation 
has ceased ? 

It is true that the decomposition of carbonic acid is arrested by 
absence of light. But then, namely, at night, a true chemical 
process commences, in consequence of the action of the oxygen 
in the air, upon the organic substances composing the leaves, 
blossoms, and fruit. This process is not at all connected with the 
life of the vegetable organism, because it goes on in a dead plant 
exactly as in a living one. 

The substances composing the leaves of different plants being 
known, it is a matter of the greatest ease and certainty to calcu- 
late which of them, during life, should absorb most oxygen by 
chemical action when the influence of light is withdrawn. 

The leaves and green parts of all plants containing volatile 
oils or volatile constituents in general, should absorb more than 
other parts free from such substances ; for these change into resin 
by the absorption of oxygen. Leaves, also, containing either the 
constituents of nut-galls, or compounds in which nitrogen is 
present, ought to absorb more oxygen than those destitute of such 



INFLUENCE OF THE SHADE ON PLANTS. aa 

matters. The correctness of these inferences has been distinctly 
proved by the observations of De Saussure ; for whilst the taste- 
less and inodorous fleshy leaves of the Agave Americana absorb 
only 0.3 of their volume of oxygen in the dark, during twenty- 
four hours, the leaves of the Pinus Abies, containing volatile and 
resinous oils, absorb ten times ; those of the Quercus Robur con- 
taining tannic acid 14 times ; and the balmy leaves of the Popu- 
lus alba 21 times that quantity. This chemical action is shown 
very plainly also in the leaves of the Cotyledon calycinum, the 
Cacalia Jicoides, and others ; for they are sour like sorrel in the 
morning, tasteless at noon, and bitter in the evening. The forma 
tion of acids is effected during the night by a true process of oxi- 
dation ; they are deprived of their acid properties during the day 
and evening, and are changed by separation of a part of their 
oxygen into compounds containing oxygen and hydrogen, either 
in the same proportions as in water, or even with an excess of 
hydrogen ; for such is the composition of all tasteless and bitter 
substances. 

Indeed the quantity of oxygen absorbed could be estimated 
pretty nearly by the different periods which the green leaves of 
plants require to undergo alteration in color by the influence of 
the atmosphere. Those continuing longest green will abstract 
less oxygen from the air in an equal space of time, than those 
the constituent parts of which suffer a more rapid change. It is 
found, for example, that the leaves of the Ilex aquifolinm, distin- 
guished by the durability of their color, absorb only 0.86 of their 
volume of oxygen gas in the same time that the leaves of the 
poplar absorb 8, and those of the beech 9^ times their volume : 
both the beech and poplar being remarkable for the rapidity and 
ease with which the color of their leaves changes. (De 
Saussure.) 

When the green leaves of the beech, the oak, or the holly, are 
dried under the air-pump, with exclusion of light, then moistened 
with water, and placed under a glass globe filled with oxygen, 
they are found to absorb that gas in proportion as they change in 
color. The chemical nature of this process is thus completely 
established. The diminution of the gas which occurs can only 
be owing to the union of a large proportion of oxygen with 



24 OF THE ASSIMILATION OF CARBON. 

those substances already in the state of oxides, or to the oxida. 
tion of such vegetable compounds as contain hydrogen in excess. 
The fallen brown or yellow leaves of the oak contain no longer 
tannin, and those of the poplar are destitute of balsamic consti- 
tuents. 

The property possessed by green leaves of absorbing oxygen 
belongs also to fresh wood, whether taken from a twig or from 
the interior of the trunk of a tree. When fine chips of such wood 
are placed in a moist condition under a jar filled with oxygen, 
the gas is seen to diminish in volume. But wood, dried by ex- 
posure to the atmosphere and then moistened, converts the 
oxygen into carbonic acid, without change of volume ; fresh 
wood, therefore, absorbs most oxygen.* 

MM. Petersen and Schodler have shown, by the careful ele- 
mentary analysis of 24 different kinds of wood, that they contain 
carbon and the elements of water, '- ith the addition of a certain 
quantity of hydrogen. Oak woor" recently taken from the tree, 
and dried at 100° C. (212° F.\ contains 49-432 carbon, 6-06& 
hydrogen, and 44*499 oxygen 

The proportion of hydrog n necessary to combine with 44-499 
oxygen in order to form water, is ^ of this quantity, namely 
5-56 ; it is evident, thf efore, that oak wood contains -,-^2" J^iore 
hydrogen than corres' onds to this proportion. In Pinus larix, 
P. ahies, and P. piceu, the excess of hydrogen amounts to ^, and 
in Tilia europea to -J-. The quantity of hydrogen stands in some 
relation to the specific weight of the wood ; the lighter kinds of 
wood contain more of it than the heavier. In ebony wood 
(Diospyros ebenum) the oxygen and hydrogen are in exactly the 
same proportion as in water. 

The difference between the composition of the varieties of 
wood, and that of simple woody fibre, depends, unquestionably, 

* When villages situated on the banks of rivers become inundated with 
floods, this property of wood gives rise to much disease. The wood of the 
floors and the rafters of the building become saturated with water, which 
evaporates very slowly. The oxygen of the air is absorbed rapidJy by 
the moist wood, and carbonic acid is generated. The latter gas exercist.- 
a directly pernicious influence when present in air to the amount of 7 Cj 
6 per cent. 



EVOLUTION OF CARBONIC ACID DURING THE N^GHT. 25 

upon the presence of constituents, in part soluble, and in part 
insoluble, such as resin and other matters, containing a large 
proportion of hydrogen : the hydrogen of such substances being 
in the analysis of the various woods added to that of the true 
woody fibre. 

It has previously been mentioned that mouldering oak wood 
contains carbon and the elements of water, without any excess 
of hydrogen. If, in its present state, its further decay does not 
alter the volume of the air, it is certain that in the beginning of 
the process the result must have been different, for the amount 
of hydrogen present in the fresh wood has been diminished, and 
this could only have been effected by an absorption of oxygen. 

Most vegetable physiologists have connected the emission of 
carbonic acid during the night with the absorption of oxygen 
from the atmosphere, and have considered these actions as a true 
process of respiration in plants, similar to that of animals, and, 
■like it, having for its result the separation of carbon from some 
of their constituents. This opinion has a very weak and un- 
stable foundation. 

The carbonic acid, which has been absorbed by the leaves 
and by the roots, together with water, ceases to be decomposed 
on the departure of daylight ; it is dissolved in the juices which 
pervade all parts of the plant, and escapes every moment 
through the leaves in quantity corresponding to that of the watei 
which evaporates. 

A soil in which plants vegetate vigorously, contains a certain 
quantity of moisture indispensably necessary to their existence. 
Carbonic acid, likewise, is always present in such a soil, 
whether it has been abstracted from the air, or has been gene- 
rated by the decay of vegetable matter. Rain and well water, 
and also that from other sources, invariably contains carbonic 
acid. Plants during their life constantly possess the power of 
absorbing by their roots moisture, and, along with it, air or car- 
bonic acid. Is it, therefore, surprising that the carbonic acid 
should be returned unchanged to the atmosphere along with 
water, in the absence of light ; for this is known to be the cause 
of the fixation of its carbon ? 

Neither this emission of carbonic acid nor the absorption of 



26 ON THE ASSIMIL vTION 0'/ CARBON. 

oxygen has any connexion with the process of assimilation, nor 
have they the slightest relation to one another ; the one is a 
purely mechanical, the other a purely chemical process. A 
cotton wick, inclosed in a lamp containing a liquid saturated 
with carbonic acid, acts exactly in the same manner as a living 
plant in the night. Water and carbonic acid are sucked up by 
capillary attraction, and both evaporate from the exterior part 
of the wick. 

Plants living in a moist soil containing humus exhale much 
more carbonic acid during the night than those growing in dry 
situations ; they also yield more in rainy than in dry weather ; 
these facts point out to us the cause of the numerous contra- 
dictory observations made with respect to the change impressed 
upon the air by living plants, both in darkness and in common 
daylight ; but these contradictions are unworthy of considera- 
tion, as they do not assist in the solution of the main question. 

There are other facts which prove in a decisive manner that 
plants yield more oxygen to the atmosphere than they extract 
from it. These proofs may easily be obtained, without having 
recourse to any peculiar arrangements, from observations made 
on plants living under water. 

Pools and ditches, the bottoms of which are covered with 
growing plants, often freeze upon their surface in winter, so 
that the water is completely excluded from the atmosphere b} 
a clear stratum of ice ; under such circumstances small bubbles 
of gas are observed to escape continually during the day, from 
the points of the leaves and twigs. These bubbles are seen 
most distinctly when the rays of the sun fall upon the ice ; they 
are very small at first, but collect under the ice and form largei 
bubbles. They consist of pure oxygen gas. Neither during 
the night, nor during the day when the sun does not shine, are 
they observed to diminish in quantity. The source of this 
oxygen is the carbonic acid absorbed by the plants from the 
water, to which it is again supplied by the decay of vegetable 
substances contained in the soil. If these plants absorb oxygen 
during the night, it can be in no greater quantity than that which 
the surrounding water holds in solution ; for the gas, which has 
been exhaled, is not again absorbed. 



hVOLUTION OF CARBONIC ACID DURING THE NIGHT. 21 

Sir H. Davy made an elegant experiment in illustration of the 
facts just stated. He placed a turf, four inches square, in a 
porcelain dish which swam on the surface of water impregnated 
with carbonic acid gas. A glass vessel of the capacity of 230 
cubic inches was made to cover the grass, to which water was 
occasionally supplied by a funnel furnished with a stopcock. 
The water upon which the porcelain dish swam was daily sup- 
plied with new water saturated with carbonic acid, so that a 
small quantity of that gas must always have been present in the 
receiver. The volume of air in the receiver was found to in- 
crease by exposure to daylight, so much so, that after the lapse 
of eight days, an increase of thirty cubic inches was observed. 
The air inside the receiver on being analysed was found to con- 
tain 4 per cent, more oxygen than the air of the exterior 
atmosphere. (Davy's Agricultural Chemistry, Lecture V.) In 
confirmation of the same facts we may also refer to the excellent 
experiments of Dr. Daubeny.* 

In the preceding part of the work, we have furnished proofs 
'chat the carbon of plants is derived from the atmosphere. We 
have yet to consider the action of humus and of certaivi mineral 
matters upon the development of vegetation, and also the source 
whence plants receive their nitrogen, 

* On the Action of Light upon Plants, ; nd of Plants upon the Atmoe* 
phere, Phil Trans., Part I., 1836 



:e ON THE ORIGIN AND ACTION OF HUMUS. 



CHAPTER III. 

On the Origin and Action of Humus. 

It will be shown in the second part of this work, that all plants 
and vegetable structures undergo two processes of decomposition 
after death. One of these is named feivnenfation, or putrefaction ; 
the other decay or eremacausis.* 

It vvill likewise be shown, that decay is a slow process of com- 
bustion, — a process, therefore, in which the combustible parts of 
a plant unite with the oxygen of the atmosphere. 

The decay of woody fibre (the principal constituent of all 
plants) is accompanied by a phenomenon of a peculiar kind. 
This substance, in contact with air or oxygen gas, converts the 
latter into on equal volume of carbonic acid, and its decay ceases 
upon the disappearance of the oxygen. If the carbonic acid be 
removed, and oxygen replaced, its decay recommences, that is, 
it again converts oxygen into carbonic acid. Woody fibre con- 
sists of carbon and the elements of water ; and if we judge only 
from the products formed during its decomposition, and from 
those formed by pure charcoal, burned at a high temperature, 
we might conclude that the causes were the same in both : the 
decay of woody fibre proceeds, therefore, as if no hydrogen or 
oxygen entered into its composition. 

A very long time is required for the completion of this process 
of combustion, and the presence of water is necessary for its 
maintenance : alkalies promote it, but acids retard it ; all anti- 
septic substances, such as sulphurous acid, the mercurial salts, 
empyreumatic oils, &:c., cause its complete cessation. 

* The word eremacausis was proposed by the author some time since, 
in order to explain the true nature of decay ; it is compounded from 
f/^i/ia, by degrees, and kaiois, burning. 



IT EVOLVES CARBONIC ACID. 29 

Woody fibre in a state of decay is the substance called 

HUMUS.* 

The property of woody fibre to convert surrounding oxygen 
gas into carbonic acid diminishes in proportion as its decaj 
advances, and at last a certain quantity of a brown coaly-looking 
substance remains, in which this property is entirely wanting. 
This substance is called mould ; it is the product of the complete 
decay of woody fibre. Mould constitutes the principal part of 
all the strata of brown coal and peat. By contact with alkalies, 
such as lime or ammonia, a further decay of mould is occa- 
sioned. 

Humus acts in the same manner in a soil permeable to air ds 
in the air itself; it is a continued source of cai'bonic acid, which 
it emits very slowly. An atmosphere of carbonic acid, formed 
at the expense of the oxygen of the air, surrounds every particle 
of decaying humus. The cultivation of land, by tilling and 
loosening the soil, causes a free and unobstructed access of air. 
An atmosphere of carbonic acid is therefore contained in every 
fertile soil, and is the first and most important food for the young 
plants growing upon it. 

In spring, when those organs of plants are absent which nature 
has appointed for the assumption of nourishment from the atmo- 
sphere, the component substances of the seeds are exclusively 
eirployed in the formation of the roots. Each new radicle fibril 
acquired by a plant may be regarded as constituting at the same 
time a mouth, a lung, and a stomach. The roots perform the 
functions of the leaves from the first moment of their formation : / 
they extract from the soil their proper nutriment, namely, the ' 
carbonic acid generated by the humus. 

By loosening the soil surrounding young plants, we favor the 
access of air, and the formation of carbonic acid ; and, on the 
other hand, the quantity of their food is diminished by every 
difficulty which opposes the renewal of air. A plant itself effects 
this change of air at a certain period of its growth. The car. 
bonic acid, which protects the undecaycd humus from further 

* The humic acid of chemists is a product of the decompositioti ot 
humus by alkalies ; it does not exiit in the humus of vegetable physiolo- 
gists. 



so ON THE ORIGIN AND ACTION OF HUMUS. 

change, is absorbed and taken away by the fine fibres of the 
roots, and by the roots themselves ; this is replaced by atmo- 
spheric air, which, by its oxygen, renews the process of decay, 
and forms a fresh portion of carbonic acid. A plant at this time 
receives its food both by the roots and by the organs above 
ground, and advances rapidly to maturity. 

When a plant is quite matured, and when the organs by which 
it obtains food from the atmosphere are formed, the carbonic acid 
of the soil is no further required. 

Deficiency of moisture in the soil, or its complete dryness, 
does not now check the growth of a plant, ~ provided it receives 
from the dew and from the atmosphere as much as is requisite for 
the process of assimilation. During the heat of summer it derives 
its carbon exclusively from the atmosphere. 

We do not know what height and strength nature has allotted 
to plants ; we are acquainted only with the size which they 
usually attain. Oaks are shown, both in London and Amsterdam, 
as remarkable curiosities, which have been reared by Chinese 
gardeners, and are only one foot and a half in height, although 
their trunks, barks, leaves, branches, and whole habitus, evince 
a venerable age. The small parsnep grown at Teltow,* when 
placed in a soil which yields as much nourishment as it can take 
up, increases to several pounds in weight. 

The size which a plant acquires in a given time is pro- 
portional TO the surface of the organs destined to convet 
GOOD to it. When the surfaces of two plants are equal, their 
mcrease depends upon the length of time that their absorbing 
powers remain in activity. The absorbing surfaces of fir trees 
are active during the greater part of the year, so that (cccteris 
paribus), they increase more than those trees which part with 
their foliage in autumn. Each leaf furnishes to a plant another 
mouth and stomach. 

The power possessed by roots of taking up nourishment does 
not cease as long as nutriment is present. When the food of a 
plant is in grctor quantity than its organs require for their own 

* Teltow is a village near Berlin, where small parsneps are cultivated 
in a sandy soil : they are much esteemed, and weigh rarely above on« 
ounce. 



GROWTH OF PLANTS. 31 

^■c'^izt development, the superfluous nutriment is not returned to 
\i.e soil, but is employed in the formation of new organs. The 
cont-nued supply of carbonic acid by means of a soil rich in 
numus must exert a very marked influence on the progressive 
cevelopment of the plant, provided the other conditions necessary 
10 the assimilation of carbon are also present. At the side of a 
cell already formed, another cell arises ; at the side of a twig 
and leaf, a new twig and a new leaf are developed. These new 
parts could not have been formed had there not been an excess 
of nourishment. The sugar and mucilage produced in the seeds, 
form the nutriment of the young plants, and disappear during the 
development of the buds, green sprouts, and leaves. 

The power of absorbing nutriment from the atmosphere, with 
which the leaves of plants are endowed, being proportionate to 
the extent of their surface, every increase in the size and number 
of these parts is necessarily attended with an increase of nutri- 
tive power, and a consequent further development of new leaves 
and branches. Leaves, twigs, and branches, when completely 
matured, as they do not become larger, do not need food for their 
support. For their existence as organs, they require only the 
means necessary for the performance of the special functions to 
which they are destined by nature ; they do not exist on their 
own account. 

We know that the functions of the leaves and other green 
parts of plants are to absorb nutritive matters from the atmo- 
sphere, and, with the aid of light and moisture, to appropriate 
their elements. These processes are continually in operation : 
they commence with the first formation of the leaves, and do not 
cease with their perfect developmei?,t. But the new products 
arising from this continued assimilation are no longer employed 
by the perfect leaves in their own increase : they serve for the 
formation of woody fibre, and all the solid matters of similar 
composition. The leaves now produce sugar, amylin or starch, 
and acids, which were previously forined by the roots when they 
were necessary for the development of the stem, buds, leaves, 
and branches of the plant. 

The organs of assimilation, at this period of their life, receive 
more nourishment from the atmosphere than they employ in their 



32 ON THE ORIGIN AND ACTION OF HUMUS 

own sustenance ; and when the formation of the woody feU'>. 
stance has advanced to a certain extent, the expenditure of the 
nutriment, the supply of which still remains the same, takes & 
new direction, and blossoms are produced. The functions of the 
leaves of most plants cease upon the z'ipening of their huh, 
because the products of their action are no longer needed. They 
now yield to the chemical influence of the oxygen of the air, 
generally suffer a change ia color, and fall off. 

A peculiar transformation of the matter contained in all 
plants takes place in the period between blossoming and the 
ripening of the iTuit ; new compounds are produced, which 
furnish constituents to the blossoms, fruit, and seeds. 

Transformations of existing compounds are constantly taking 
place during the whole life of a plant, in consequence of which, 
and as the results of these transformations, there are produced 
gaseous matters which are excreted by the leaves and blossoms, 
solid excrements deposited in the bark, and fluid soluble substan- 
ces which are eliminated by the roots. Such secretions are most 
abundant immediately before the formation and during the con- 
tinuance of the blossoms ; they diminish after the development 
of the fruit. Substances containing a large proportion of carbon 
are excreted by the roots and absorbed by the soil. Through 
the expulsion of these matters unfitted for nutrition, the soil 
receives again the greater part of the carbon which it had at first 
yielded to the young plants as food, in the form of carbonic acid. 

The soluble matter thus acquired by the soil is still capable 
of decay and putrefaction, and, by undergoing these processes, 
furnishes renewed sources of nutrition to another generation oi 
plants ; it becomes humus. The fallen leaves of trees, and the 
old roots of grass in the meadow, are likewise converted into 
humus by the same influence. 

The carbon contained in the roots of annual plants, such as 
the corn plants and culinary vegetables, is without doubt derived 
principally from the atmosphere. But after the removal of the 
crop, their roots remain in the soil, and, undergoing putrefaction 
and decay, furnish humus, or that substance which is able to 
yield carbonic acid to a new vegetation. A soil receives more 



NOT INDISPENSABLE FOR PLANTS. 33 

carbon in this form, than its decaying humus had formerly lost 
in carbonic acid. 

Plants do not exhaust the carbon of a soil in the normal con. 
dition of their growth ; on the contrary, they add to its quantity. 
But if it be true that plants give back more carbon to a soil than 
they take from it, it is evident that the amount of carbon which 
is removed in any shape in the crop must have been derived from 
the atmosphere in the form of carbonic acid. It is well known 
that springs occurring in gardens of the richest vegetable mould, 
furnish clear and perfectly colorless water destitute both of 
humus and of salts of humic acid. It is likewise known that 
humates cannot be detected in the springs of meadows, in the 
waters of our rivers, or even in acidulous mineral waters, 
although they contain a considerable quantity of alkaline salts. 
Now a simple consideration of these facts proves to us either that 
the richest vegetable mould is free from humic acid, or that this 
acid cannot be absorbed by plants through the agency of water. 
Hence it follows that the common view of the action of humus is 
erroneous. The water resting upon a meadow is found to be 
iich in carbonic acid and alkaline bases. Well-water also gene- 
rs,!!y contains much of the former ingredient. The influence, 
iheii, of humus or decaying vegetable matter upon vegetation, is 
explained by these facts in the most clear and satisfactory man- 
ner. Humus, therefore, does not nourish plants by being assimi- 
lated in its soluble state, but by furnishing a gradual and conti- 
nued source of carbonic acid. This gas forms the chief means of 
nourishment to the roots of plants, and is constantly formed anew 
as long as the soil admits the free access of air and moisture, 
these being the necessary conditions for effecting the decay ol 
vegetable matter. 

The verdant plants of warm climates are very often such as 
obtain from the soil only a point of attachment, and are not de- 
pendent on it for their growth. How extremely small are the 
roots of the various species of Cactus,* Sedum, and Sejupervivuni, 

* The Cactus was probably introduced into Sicily by the Spaniards. It 

forms as important an article of diet with the inhabitants of that island as 

the poCatoe does with ourselves. This abundant, cooling, and juicy fruit 

forms the principal food of the lower classes for three months, and is con- 

3* 



34 ON THE ORIGIN AND ACTION OF HTTMU3. 

in proportion to their mass, and to the surface of their leaves 
Large forests are often found growing in soils absolutely desti- 
tute of carbonaceous matter : and the extensive prairies of the 
Western Continent show that the carbon necessary for the suste- 
nance of a plant may be entirely extracted from the atmosphere. 
Again, in the most arid and barren sand, where it is impossible 
for nourishment to be obtained through the roots, we see the 
milky-juiced plants attain complete perfection. The moisture 
necessary for the nutrition of these plants is derived from the 
atmosphere, and when assimilated is secured from evaporation 
by the nature of the juice itself. Caoutchouc and wax, which 
are formed in these plants, surround the water, as in oily emul- 
sions, with an impenetrable envelope by which the fluid is 
retained, in the same manner as milk is prevented from evapo- 
rating by the skin which forms upon it. The plants become 
turgid with their juices. 

sidered very palatable, although strangers usually find it insipid. The 
hills of Palermo covered with the Cactus correspond to our corn-fields. 
It is a very important plant for such districts, because its roots easily enter 
into the cracks and crevices of the volcanic rocks. These, although 
destitute of humus, soon acquire it by the decay of thie leaves, and *hus 
fertile soils are gradually formed for other plants. {Auslande, S. 274, 
3d October, 1S42.) 



ASSIMILATION OF HYDROGEN. 35 



CHAPTER IV. 

On the Assimilation of Hydrogen. 

The atmosphere contains the principal food of plants in the 
form of carbonic acid, in the state, therefore, of an oxide. The 
solid part of plant" (woody fibre) contains carbon and the consti- 
tuents of water, or the elements of carbonic acid, together with a 
certain quantity of hydrogen. It has formerly been mentioned 
that water consists of the two gases, oxygen and hydrogen. We 
can conceive the wood to arise from a combination of the 
carbon of the carbonic acid with the elements of water, under 
the influence of solar light. In this case, 72*35 parts of oxygen, 
by weight, must be separated as a gas for every 27-65 pai'ts of 
carbon assimilated by a plant ; for this is the composition of car- 
bonic acid in 100 parts. Or, what is much more probable, 
plants, under the same circumstances, may decompose water, in 
which case the hydrogen would be assimilated along with car. 
bonic acid, whilst its oxygen would be separated. If the latter 
change takes place, 9-77 parts of hydrogen must unite with 100 
parts of carbonic acid in order to form woody fibre, and the 
72-35 parts by weight of oxygen, which was in combination with 
the hydrogen of the Mater, and which exactly corresponds in 
quantity with the oxygen contained in the carbonic acid, must 
be separated in a gaseous form.* 

Each acre of land, producing 10 cwts. of carbon, gives 

* As far as regards the final results, it is a matter of perfect indifler- 
ence to which of these views we accord the preference. Hence we will 
use both occasionally. The decomposition of carbonic acid, as well as 
that of water, must be supposed in the formation of those compounds 
in which oxygen is either entirely absent or insufficient to form water 
with the hydrogen. 



36 ASSIMILATION OF HYDROGii^N. 

annually to the atmosphere 2865 lbs., or 32,007 cubic feet of 
free oxygen gas.* 

An acre of meadow, wood, or cultivated land, in general re- 
places, therefore, in the atmosphere as much oxygen as ia 
exhausted by 10 cwts. of carbon, either in its ordinary combus- 
tion in the air, or in the respiratory process of animals. 

It has been mentioned in a former part of the work that pure 
woody fibre contains carbon and the component parts of water, 
but that ordinary wood contains more hydrogen than corresponds 
to this proportion. This excess is owing to the presence of the 
green principle of the leaf, wax, oil, resin, and other bodies rich 
in hydrogen. Water must be decomposed, in order to furnish 
the excess of this element, and consequently one equivalent of 
oxygen must be given back to the atmosphere for every equiva- 
lent of hydrogen appropriated by a plant to the production of 
those substances. The quantity of oxygen thus set at liberty 
cannot be insignificant, for the atmosphere must receive above 
100 cubic feet of oxygen for every pound of hydrogen 
assimilated. 

It has already been stated, that a plant, in the formation of 
woody fibre, must always yield to the atmosphere the same pro- 
portional quantity of oxygen ; and that the volume of this gas 
set free would be the same whether it were due to the decompo- 
sition of carbonic acid or of water. It was considered most pro- 
bable that the latter was the case. 

From their generating caoutchouc, wax, fats, and volatile oils 
containing hydrogen in large quantity, and little oxygen, we may 
be certain that plants possess the property of decomposing 
water, because from no other body could the unazotized sub- 
stances obtain their hydrogen. It has also been proved by the 
observations of Humboldt on the fungi, that water may be decom- 
posed without the assimilation of hydrogen. Water is a remark- 
able combination of two elements, which have the power to sepa- 
rate themselves from one another, in innumerable processes, in 
a manner imperceptible to our senses ; while carbonic acid, 

* The specific weight of oxygen is expressed by the number 1"1026 ; 
hence, 1 cubic metre of oxygen w^eighs 3'157 lbs., and 2865 lbs. of oxygen 
cprrespond to 908 cubic metres, or 32,007 cubic feet. 



'.SSIMILATION OF HYDROGEN. ST 

on the contrary, is only decomposable by violent chemical 
action. 

Most vegetable structures contain hydrogen in the form of 
water, which can be separated as such, and replaced by other 
bodies ; but the hydrogen essential to their constitution cannot 
possibly exist in the state of water. 

All the hydrogen necessary for the formation of an organic 
compound is supplied to a plant by the decomposition of water. 
The process of assimilation, in its most simple form, consists in the 
extraction of hydrogen from water, and of carbon from carbonic 
acid, in consequence of which, either all the oxygen of the 
water and of the carbonic acid is separated, as in the formation 
of caoutchouc, the volatile oils containing no oxygen, and other 
similar substances, or only a part of it is exhaled. 

The known composition of the organic compounds most gene 
rally present in vegetables, enables us to state in definite propor 
tions the quantity of oxygen separated during their formation. 

36 eq. carbonic acid and 22 eq. hydrogen derived } —ffToodv Fibre * 
from 22 eq. water ----- 5 

with the separation of 72 eq. oxygen. 
36 eq. carbonic acid and 36 eq. hydrogen derived ) r=Suffar 

from 36 eq. water 5 

with the separation of 72 eq. oxygen. 
36 eq. carbonic acid and 30 eq. hydrogen derived > _. o*„;.»a 

from 30 eq. water 5 

with the separation of ''2 eq. oxygen. 
36 eq. carbonic acid and L6 eq. hjiroge.i derived ) —.y^^j^jV jidd 
from 16 eq. water ----- ^ 

with the separation of 64 eq oxygen. 
36 eq. carbonic acid and 18 eq. hydrogen derived ^ _ jp^^^^^.^^ Acid 
from 18 eq. water ----- j 

with the separation of 45 eq. oxygen. 
36 eq. carbonic acid and 18 eq. hydrogen derived ) _ jj^^^j^ ji^j 

from IS eq. water 5 

with the separation of 54 eq. oxygen. 

* It is evident that both carbonic acid and water must be decomposed 
to yield woody fibre of the above composition, C36 H22 O22 ; that is, if 
water is here decomposed. For 22 eq. of water can only yield 22 eq. of 
oxygen ; and, therefore, supposing all the water to be decomposed, 25 of 
the 36 eq of carbonic acid must also be decomposed, to yield, with the 
oxygen of the 22 eqs. ol water, 72 eq. of oxygen. The remaining 11 eqs 
of carbonic acid with the carbon of the 25 eq. decomposed, and the 22 eqs 
of hydrogen will then yield the residue Cs 6 H2 e O2 2. 



38 ASSIMILATION OF HYDROGEN. 

30 eq. carbonic acid and 24 eq. hydrogen derived ) — mj „frr,,r„pnHnp 

from 24 eq. water ^—uuojiurpentme. 

with the separation of 84. eq. oxygen. 

It will readily be perceived that the formation of the acids ia 
accompanied with the smallest separation of oxygen; that the 
amount of oxygen set free increases with the production of the 
so-named neutral substances, and reaches its maximum in the 
formation of the oils. Fruits remain acid in cold summers ; 
while the most numerous trees under the tropics are those which 
produce oils, caoutchouc, and other substances containing very 
little oxygen. The action of sunshine and influence of heat 
upon the ripening of fruit is thus, in a certain measui'e, repre- 
sented by the numbers above cited. 

The green resinous principle of the leaf diminishes in quan- 
tity, while oxygen is absorbed, when fruits are ripened in the 
dark ; red and yellow coloring matters are formed ; tartaric, 
citric, and tannic acids disappear, and are replaced by sugar, 
amylin, or gum. 6 eq. Tartaric acid, by absorbing 6 eq. oxygen 
from the air, form grape sugar, with the separation of 12 eq. 
carbonic acid, 1 eq. Tannic Acid, by absorbing 8 eq. oxygen 
from the air, and 4 eq. water, form 1 eq. of Amylin, or starch, 
with separation of 6 eq. carbonic acid. 

We can explain, in a similar manner, the formation of all the 
unazotized component substances of plants, whether they are 
produced from carbonic acid and water, with the separation of 
oxygen, or by the conversion of one substance into the other, 
by the assimilation of oxygen and separation of carbonic acid. 
We do not know in what form the production of these constitu- 
ents takes place ; in this respect, the representation of their 
fDrmation which we have given must not be received in an 
absolute sense, it being intended only to render the nature of 
the process more capable of apprehension ; bat i' must not be 
forgotten, that if the conversion of tartaric acid into sugar, in 
grapes, be considered as a fact, it must take place under hH cir- 
cumstances in the proportions above mentioned. 

The vital process in plants is, ^ith reference to the point we 
have been considering, the converse of the chemical processes 
engaged in the formation of salts. Carbonic acid, zinc, and 



ATTENDED WITH EVOLUTION OF OXYGEN. 39 

water, when brought into contact, act upon one another, and 
HYDROGEN IS SEPARATED, while a white pulverulent compound ia 
formed, which contains carbonic acid, zinc, and the oxygen of 
the water. A living plant represents the zinc in this process ' 
but the process of assimilation gives rise to compounds, which 
contain the elements of carbonic acid and the hydrogen of 
water, whilst oxygen is separated. 

Decay has been described above as the great operation of na- 
ture, by which that oxygen which was assimilated by plants 
during life, is again returned to the atmosphere. During the 
progress of growth, plants appropriate carbon in the form of 
carbonic acid, and hydrogen from the decomposition of water, 
the oxygen of which is set free, together with a part or all of 
that contained in the carbonic acid. In the process of putrefac- 
tion, a quantity of wa,ter, exactly corresponding to that of the 
hydrogen, is again formed by extraction of oxygen from the air ; 
while all the oxygen of the organic matter is returned to the 
atmosphere in the f^rm of carbonic acid. Vegetable matters 
can emit carbonic acid, during their decay, only in proportion 
to the quantity of oxygen which they contain ; acids, therefore, 
yield more carbonic acid than neutral compounds ; while fatty 
acids, resin, and wax, do not putrefy ; t ley remain in the soil 
without any apparent change. 



40 SOURCE AxNTD ASSIMILATION OF NITROGEN. 



CHAPTER V. 

On the Origin and Assimilation of Nitrogen. 

We cannot suppose that a plant could attain maturity, even in 
the richest vegetable mould, without the presence of mattei 
containing nitrogen ; since we know that nitrogen exists in 
every part of the vegetable structure. The first and most im- 
portant question to be solved, therefore, is : How and in what 
form does nature furnish nitrogen to vegetable albumen, and to 
gluten, or to fruits and seeds ? * 

This question is susceptible of a very simple solution. 

Plants, as we know, grow perfectly well in a mixture of char- 
coal and earth, previously calcined, if supplied at the same time 
with rain-water. Rain-water can contain nitrogen only in three 
forms, as dissolved atmospheric air, as nitric acid, or as ammonia. 
Now, the nitrogen of the air cannot be made to enter into combi- 
nation with any element except oxygen, even by the employment 
of the most powerful chemical means. We have not the slight- 
est reason for believing that the nitrogen of the atmosphere takes 
part in the processes of assimilation of plants and animals ; on the 
contrary, we know that many plants emit the nitrogen which is 
absorbed by their roots, either in the gaseous form, or in solution 
in water. But there are on the other hand numerous facts, 
showing, that the formation in plants of substances containing 
nitrogen, such as gluten, takes place in proportion to the quantity 

* " It is certain," says Saussure, "from the experiments which have 
been made on this point, that plants receive their nitrogen only from such 
animal or vegetable extracts, or from such ammoniacal vapors as they may 
find in the soil, or extract from the air. When plants are made to 
vegetate by the aid of water in a confined atmosphere, we may presume 
that the new parts can only obtain nitrogen at the expense of otlier parts 
to which it had formerly been supplied." {De Saussure, page 190.) 



SOURCE AND ASSIMILATION OF NITROGEN. 4J 

of this element conveyed to their roots in the state of ammonia, 
derived from the putrefaction of animal matter. 

Ammonia, too, is capable of undergoing such a multitude of 
transformations, when in contact with other bodies, that in this 
respect it is not inferior to water, which possesses the same pro- 
perty in an eminent degree. It possesses properties which we 
do not find in any other compound of nitrogen j when pure, it is 
extremely soluble in water ; it forms soluble compounds with all 
the acids ; and when in contact with certain other substances, it 
completely resigns its character as an alkali, and is capable of 
assuming the most various and opposite forms. Formate of am- 
monia changes, under the influence of a high temperature, into 
hydrocyanic acid and water, without the separation of any of its 
elements. Ammonia forms urea, with cyanic acid, and a series 
of crystalline compounds, with the volatile oils of mustard and 
bitter almonds. It changes into splendid blue or red coloring 
matters, when in contact with phloridzin, the bitter constituent of 
the bark of the root of the apple-tree, with orcin, the sweet prin- 
ciple of the Lichen deallatus, or with erythrin, the tasteless matter 
of the Rocella tinctoria. All blue coloring matters capable of 
being reddened by acids, and all red coloring substances rendered 
blue by alkalies, contain nitrogen, but not in the form of a base. 

These facts are not sufficient to establish the opinion that it is 
ammonia which affords all vegetables, without exception, the ni- 
trogen of their constituent substances. Considerations of another 
kind, however, give to this opinion a degree of certainty which 
completely excludes all other views of the matter. 

Let us picture to ourselves the condition of a well-cultured 
farm so large as to be independent of assistance from other 
quarters. On this extent of land there is a certain quantity of 
nitrogen contained both in the corn and fruit which it produces, 
and in the men and animals which feed upon them, and also in their 
excrements. We shall suppose this quantity to be known. The 
land is cultivated without the importation of any foreign sub- 
stance containing nitrogen. Now, the products of this farm 
must be exchanged every year for money, and other necessaries 
of life — for bodies, tlierefore, destitute of nitrogen. A certain 
proportion of nitrogen is exported in the shape of corn and cat- 



42 SOURCE AND ASSIMILATION OF NITROGEN. 

tie : and this exportation takes place every year, without the 
smallest compensation : yet after a given number of years, the 
quantity of nitrogen will be found to have increased. Whence, 
we may ask, comes this increase of nitrogen ? The nitrogen in 
the excrements cannot reproduce itself, and the earth cannot yield 
it. Plants, and consequently animals, must, therefore, derive 
(heir nitrogen from the atmosphei'e. (Boussingault.) 

It will in a subsequent part of this work be shown that the 
last products of the decay and putrefaction of animal bodies pre- 
sent themselves in two different forms. They are in the form of 
ammonia (a combination of hydi'ogen and nitrogen), in the tem- 
perate and cold climates, and in that of nitric acid (a compound 
containing oxygen), in the tropics and hot climates. The forma- 
tion of the latter is always preceded by the production of the 
former. Ammonia is the last product of the putrefaction of 
animal bodies ; nitric acid is the product of the decay or erema- 
causis of ammonia. A generation of a thousand million men is 
renewed every thirty years ; thousands of millions of animals 
cease to live, and are reproduced, in a much shorter period. 
Where is the nitrogen contained in them during life ? There is 
no question which can be answered with more positive certainty. 
All animal bodies during their decay yield to the atmosphere 
their nitrogen in the form of ammonia. Even in the bodies 
buried sixty feet under ground in the churchyard of the Eglise 
des Innocens, at Paris, all the nitrogen contained in the adipocire 
was in the state of ammonia. Ammonia is the simplest of all 
the compounds of nitrogen ; and hydrogen is the element for 
which nitrogen possesses the most predominant affinity. 

The nitrogen of putrefied animals is contained in the atmo- 
sphere as ammonia, in the state of a gas which is capable of 
entering into combination with carbonic acid, and of forming a 
volatile salt. Ammonia in its gaseous form, as well as all its 
volatile compounds, is of extreme solubility in water. Ammonia, 
therefore, cannot remain long in the atmosphere, as every shower 
of rain must effect its condensation, and convey it to the surface 
of the earth. Hence also, rain-water must at all times contain 
ammonia, though not always in equal quantity. It must contain 
more in summer than in spring or in winter, because tlie inter 



PRODUCTS OF PUTREFACTION. 43 

vals of time between the showers are in summer greater ; and 
when several wet days occur, the rain of the first must contain 
more of it than that of the second. The rain of a thunder-storm, 
after a long- protracted drought, ought for this reason to contain 
the greatest quantity conveyed to the earth at one tmie. 

But all the analyses of atmospheric air hitherto made have 
failed to demonstrate the presence of ammonia, although, accord- 
ing to our view, it can never be absent. Is it possible that it 
could have escaped our most delicate and most exact apparatus ? 
The quantity of nitrogen contained in a cubic foot of air, as am- 
monia, is certainly extremely small, but, notwithstanding this, 
the sum of the quantities of nitrogen from thousands and millions 
of dead animals is more than sufficient to supply all those living 
at one time with this element. 

From the tension of aqueous vapor at 15° C. (59° F.)^0,98 
lines (Paris measure), and from its known specific gravity at 
0° C. (32'^ F.), it follows that when the temperature of the air is 
59° F. and the height of the barometer 28'''', 1 cubic metre, or 
35-3 cubic feet of aqueous vapor are contained in 48-1 cubic 
metres, or 1698 cubic feet of air ; 35-3 cubic feet of aqueous 
vapor weigh about I5 lb. Consequently, if we suppose that 
the air saturated with moisture at 59° F. allows all the water 
which it contains in the gaseous form to fall as rain, then 1 pound 
of rain-water must be obtained from every 1132 cubic feet of 
air. The whole quantity of ammonia contained in the same 
number of cubic feet will also be returned to the earth in this 
one pound of rain-water. But if the 1132 cubic feet of air con- 
tain a single grain of ammonia, then the few cubic inches usually 
employed in an analysis must contain only 0-0000048 of a 
grain. This extremely small proportion is absolutely inappre- 
ciable by the most delicate and best eudiometer ; it might be 
classed among the errors of observation, even were its quantity 
ten thousand times greater. But the detection of ammonia must 
be much more easy when a pound of rain-water is examined, 
for this contains all the gas that was diffused through 1132 cubic 
feet of air. 

If a pound of rain-water contain only :Jth of a grain of am. 
monia, then a field of 26,910 square feet must receive annually 



44 SOURCE AND ASSIMILATION OF NITROGEN. 



upwards of 80 lbs. of ammonia, or 65 lbs. of nitrogen; for by 
the observations of Schubh;r, formerly alluded to, the annual fall 
must be about 2,520,000 lbs. This is much more nitrogen than 
is contained in the form of vegetable albumen and gluten, in 
2,650 lbs. of wood, 2,500 lbs. of hay, or 200 cwt. of beet-root, 
which are the yearly produce of such a field ; but it is less than 
the straw, roots, and grain of corn, which might grow on the 
same surface, would contain. 

Experiments made in this laboratory (Giessen) with the great- 
est care and exactness, have placed the presence of ammonia in 
rain-water beyond all doubt. It has hitherto escaped obser- 
vation, because it was not searched for. All the rain-water em- 
ployed in this inquiry was collected 600 paces south-west of 
Giessen, whilst the wind was blowing in the direction of the 
town. When several hundred pounds of it were distilled in a 
copper still, and the first two or three pounds evaporated with the 
addition of a little muriatic acid, a very distinct crystallization 
of sal-ammoniac was obtained : the crystals had always a brown 
or yellow color. 

Ammonia may likewise be always detected in snow-water. 
Crystals of sal-ammoniac were obtained by evaporating in a ves- 
sel with muriatic acid several pounds of snow, which were ga- 
thered from the surface of the ground in March, when the snow 
had a depth of ten inches. Ammonia was set free from these 
crystals by the addition of hydrate of lime. The inferior layers 
of snow resting upon the ground contained a quantity decidedly 
greater than those upon the surface. 

It is worthy of observation that the ammonia contained in rain 
and snow-water possesses an offensive smell of perspiration and 
putrefying matter, — a fact which leaves no doubt respecting its 
origin. 

Hunefield has proved that all the springs in Greifswalde, Wiek, 
Eldena, and Kostenhagen, contain carbonate and nitrate of am- 
monia. Ammoniacal salts have been discovered in many m'lieral 
springs in Kissingen and other places. The ammonia of these 
Baits can only arise from the atmosphere.* 

• rharmaceutical chemists are well aware of the existence of ammonij 



EXISTENCE OF AMMONIA IN THE JUICES OF PLANTS. 49 

Any one may satisfy himself of the presence of ammonia in 
rain by simply adding a little sulphuric or muriatic acid to a 
quantity of rain-water, and hy evaporating this nearly to dryness 
in a clean porcelain basin. The ammonia remains in the residue, 
in combination with the acid employed ; and may be detected 
either by the addition of a little chloride of platinum, or, more 
simply, by a little powdered lime, which separates the ammonia; 
and thus renders sensible its peculiar pungent smell. The sen- 
sation perceived upon moistening the hand with rain-M'ater, so 
different from that produced by pure distilled water, and to which 
the term softness is vulgarly applied, is also due to the carbonate 
of ammonia contained in the former. 

The ammonia removed from the atmosphere by rain and other 
causes, is as constantly replaced by putrefaction of animal and 
and vegetable matters.* A certain portion of that which falls 
with the rain evaporates again with the water ; but another por- 
tion is, we suppose, taken up by the roots of plants, and entering 
into new combinations in the different organs of assimilation, 
produces, by the action of these and of certain other conditions, 
albumen, gluten, and vegetable casein, or quinine, morphia, 
cyanogen, and a number of other compounds containing nitrogen. 
The chemical characters of ammonia render it capable of enter- 
ing into such combinations, and of undergoing numerous trans- 
formations. We have now only to consider whether it really ia 
taken up in the form of ammonia by the roots of plants, and in 
that form applied by their organs to the production of the azotised 
matters contained in them. This question is susceptible of easy 
solution by well-known facts. 

In the year 1834, I was engaged with Dr. Wilbrand, professor 
>f botany in the University of Giessen, in an investigation re- 

m well-water, for they have often to reject as much as one-fourth of the 
water distilled, before they procure water which is not rendered turbid by 
corrosive sublimate. But when phosphoric acid or alum is added to the 
water previous to distillation, the product of the distillation is not affected 
either by corrosive sublimate or by sugar of lead. (Wiegmann and Pot- 
storf's Prize Essay on the Inorganic Ingredients of Plants.) 

* " We cannot doubt," says Saussure, " that ammonia exists in the atmo- 
iphere, for we know that sulphate of alumina is gradually converted int< 
ammoniacal alum by exposure to the air " {Eech. siir la Vigit.) 



<6 SOURCE AND ASSIMILATION OF NITROGEN. 



specting the quantity of sugar contained in difTerent varieties of 
maple-trees, growing upon unmanured soils. We obtained crys- 
tallized sugars from all, by simply evaporating their juices, with- 
out the addition of any foreign substance ; and we unexpectedly 
made the observation, that a great quantity of ammonia was emit- 
ted from this juice when mixed with lime, in the process of refin- 
ing, as practised with cane sugar. The vessels which hung upon 
the trees in order to collect the juice were watched with the 
greatest attention, on account of the suspicion that some evil-dis- 
posed persons had introduced urine into them, but still a large 
quantity of ammonia was again found in the form of neutral salts. 
The juice had no color, and had no reaction on that of vegeta- 
bles. Similar observations were made upon the juice of the 
birch tree ; the specimens subjected to experiment were taken 
from a wood several miles distant from any house, and yet the 
clarified juice, evaporated with lime, emitted a strong odor of 
ammonia. 

In the manufactories of beet-root sugar, many thousand cubic 
feet of juice are daily purified with lime, in order to free it from 
vegetable albumen and gluten, and it is afterwards evaporated 
for crystallization. Every person who has entered such a manu- 
factory must have been astonished at the great quantity of am- 
monia volatilized along with the steam. This ammonia must be 
contained in the form of an ammoniacal salt, because the neutral 
juice possesses the same characters as the solution of such a salt 
in water; it acquires, namely, an acid reaction during evapora- 
tion, in consequence of the neutral salt being converted by loss 
of ammonia into an acid salt. The free acid thus formed is a 
source of loss to the manufacturers of sugar from beet-root, by 
changing a part of the sugar into uncrystallizable grape sugar 
and syrup. 

The products of the distillation of flowers, herbs, and roots, 
with water, and all extracts of plants made for medicinal pur- 
poses, contain ammonia. The unripe, transparent, and gelatinous 
pulp of the almond and peach, emit much ammonia when treated 
with alkalies. (Robiquet.) The juice of the fresh tobacco leaf 
contains ammoniacal salts. The water which exudes from a cut 
vine, when evaporated with a few drops of muriatic acid, also 



COMPOSITION OF EXCREMENTxTIOUS MATTER. 



yields a gummy deliquescent mass, which evolves much ammo. 
nia on the addition of lime. Ammonia exists in every part of 
plants, in the roots (as in beet-root), in the stem* (of the maple, 
tree), and in all blossoms and fruit in an unripe condition. 

The juices of the maple and birch contain both sugar and am- 
monia, and therefore afford all the conditions necessary for the 
formation of the azotised components of the branches, blossoms, 
and leaves, as well as of those which contain no nitrogen. In 
proportion as the development of those parts advances, the am> 
monia diminishes in quantity, and when they are fully formed, 
the tree yields no more juice. 

The employment of animal manure in the cultivation of grain, 
and the vegetables which serve for fodder to cattle, is the most 
convincing proof that the nitrogen of vegetables is derived from 
ammonia. The quantity of gluten in wheat, rye, and barley, is 
very variable ; these kinds of grain also, even when ripe, con- 
tain this compound of nitrogen in very different proportions. 
Proust found French wheat to contain 12-5 per cent, of gluten ; 
Vogel found that the Bavarian contained 24 per cent. ; Davy 
obtained 19 per cent, from winter, and 24 from summer wheat ; 
from Sicilian 21, and from Barbary wheat 19 per cent. The 
flour of Alsace wheat contains, according to Boussingault, 17'3 
per cent, of gluten ; that of wheat grown in the " Jardin des 
Plantes," 26*7 ; and that of winter wheat, 33-3 per cent. Such 
great differences must be owing to some cause, and this we find 
in the different methods of cultivation. An increase of animal 
manure gives rise not only to an increase in the number of seeds, 
hut also to a niost remarkable difference in the proportion of the 
substances contaming nitrogen, such as the gluten. 

Animal manure exerts a very complex action on plants, but as 
far as regards the assimilation of nitrogen, it acts only by the 
formation of ammonia. One hundred parts of wheat grown on 
a soil manured with cow-dung (a manure containing the smallest 
quantity of nitrogen), afforded only 11-95 parts of gluten, and 
62-34 parts of amylin, or starch ; whilst the same quantity, 

• In an experiment performed at my reqiipat in Calcutta, it was found 
that the fresh juice of the palm tree abounded with ammonia.— JEd. 



48 SOURCE AND ASSIMILATION OF NIGROGEN. 

grown on a soil manured with human urine, yielded the maxi- 
mum of gluten, namely 35-1 per cent., or nearly three times the 
quantity. Putrefied urine contains nitrogen ia the forms of 
carbonate, phosphate, and muriate of ammonia, and in no other 
form than that of ammoniacal salts. 

Putrid urine is employed in Flanders as a manure, with the 
best results. During the putrefaction of urine, ammoniacal salts 
are formed in large quantity, it may be said exclusively ; for 
under the influence of heat and moisture, urea, the most promi- 
nent ingredient of the urine, is converted into carbonate of am- 
monia. The barren soil on the coast of Peru is rendered fertile 
by means of a manure called Guano, which is collected from 
several Islands in the South Sea.* It is sufficient to add a small 
quantity of guano to a soil consisting only of sand and clay, in 
order to procure the richest crop of maize. The soil itself does 
not contain the smallest particle of organic matter, and the ma- 
nure employed is formed only of urate, phosphate, oxalate, and 
carbonate of ammonia, together with salts. f 

The ammonia, therefore, of the salts contained in Guano, must 
have yielded the nitrogen to these plants. Gluten is obtained 
from corn ; vegetable albumen from certain juices, such as from 
the expressed juice of the grape ; vegetable casein occurs in the 
seeds of the leguminous plants ; but although all these have dif- 
ferent names and properties, they are identical in composition 
with the ordinary gluten. 

It is then ammonia which yields nitrogen to the vegetable albu- 
men, the principal azotised constituent of plants. Nitrogen is 
not presented to wild plants in any other form capable of assimi- 
lation. Ammonia, by its transformation, furnishes nitric acid to 
the tobacco-plant, sunflower, Chenopodium, and Borago officinalis, 
when they grow in a soil completely free from nitre. Nitrates 
are necessary constituents of these plants, which thrive only 
when ammonia is present in large quantity, and when they are 

* The guano, which forms a stratum several feet in thickness upon the 
surface of these islands, consists of the putrid excrements of innumerable 
Bea fowl that remain on them during the breeding season. (See tb# 
Chapter on Manures.) 

t Boussingault, Ann. de Ch. et de Phys., Ixv., p. ol^i 



FORM IN WHICH AMMONIA IS PRESENTED. 49 



also subject to the influence of the direct rays of the sun ; an 
.nfluence necessary to effect the disengagement within their stem 
and leaves of the oxygen which shall unite with the ammonia to 
form nitric acid. 

The urine of men and of carnivorous animals contains the 
largest quantity of nitrogen, partly in the form of phosphates, 
partly as urea. Urea is converted dui'ing putrefaction into car- 
bonate of ammonia, that is to say, it takes the form of the very 
salt in rain-water. Human urine is the most powerful manure 
for vegetables rich in nitrogen ; the urine of cattle, sheep, and 
horses, contains less nitrogen ; but yet far more than the solid 
excrements of these animals. In addition to urea, the urine of 
herbivorous animals contains hippuric acid, which is decomposed 
during putrefaction into benzoic acid, and ammonia. The latter 
causes the formation of gluten, but the benzoic acid often remains 
unchanged : for example, in the Anthoxanthum odoratum. 

The solid excrements of men and of animals contain compara- 
tively very little nitrogen, but this could not be otherwise. The 
food taken by animals supports them only in so far as it offers to 
the various organs elements for assimilation which they may 
require for their increase or renewal. Corn, grass, hay, and all 
plants, without exception, whether fresh or dried, contain highly 
azotised substances. The quantity of food required by animals 
for their nourishment diminishes or increases in the same propor- 
tion as it contains more or less of the substances containing 
nitrogen. A horse may be kept alive by feeding it with 
potatoes, a food containing a very small quantity of nitrogen ; 
but life thus supported is a gradual starvation ; the animal 
increases neither in size nor strength, and sinks under every 
exertion. The quantity of rice consumed by an Indian astonishes 
the European ; but the fact that rice contains less nitrogen than 
.>any other kind of grain at once explains the circumstance. 

Now, as it is evident that the nitrogen of the plants and seeds 
used by animals as food must be employed in the process of 
assimilation, it is natural to expect that the solid excrements of 
the^e animals will be deprived of it in proportion to the perfect 
digestion of the food, and can only contain it when mixed with 
fiecretions from the liver and intestines Under all circumstan- 
4 



50 SOURCE AND ASSIMILATION OF NITROGEN. 



ces, they must contain less nitrogen than the food. When, 
therefore, a field is manured with animal excrements, a smaller 
quantity of matter containing nitrogen is added to it than hag 
been talten from it in the form of grass, herbs, or seeds. There- 
fore, it follows that the favorable activity of such manure cannot 
be due to its nitrogen. 

The liquid manure of animals must, on the other hand, be of 
the highest value with respect to nitrogen : because it contains 
all or nearly all the nitrogen originally present in the food con- 
sumed. In order to comprehend more clearly the importance 
of liquid excrements, it is necessary to consider the manner in 
which they are formed. 

It is well known that the body of an adult man, or of an animal 
in a state of health, remains constantly the same, and neither 
diminishes nor increases in weight to any appreciable extent. 
In youth the case is different ; for an increase of the body is 
occasioned. The same is the case in the artificial process of 
fattening. The body of the old man, on the other hand, gra- 
dually diminishes in size. 

The quantity of nitrogen and of other constituents in the body 
cannot therefore increase, although the animal always receives 
in his food a considerable quantity of that element. From this 
it follows, that the quantity of nitrogen expelled from the body 
must be the same as that taken in the food by an animal in a 
state of nature, freely exposed to exercise ; for if this were not 
the case, the body must acquire a larger proportion of nitrogen, 
which we know it does not. 

When an individual is deprived of food and in the progress of 
starvation, his body diminishes in weight, in such a manner that 
all parts, except the membranes and bones, participate in the 
loss. By what means has the nitrogen of those tissues been 
expelled from the system ? 

The emaciation which occurs proves that during every moment 
in the life of an animal, part of its structure loses its vitality, and 
assumes the form of dead matter. This, after suffering certain 
changes, is finally separated from the system by the organs of 
secretion, namely, the skin, lungs, and kidneys. The daily losi 
thus experienced is restored by food. 



FORM IN WHICH AMMONIA IS PRESENTED. 51 



The azotised constituents of the food are transformed into 
blood, which then nourishes the animal by restoring its vvasteo 
tissues to their original condition. 

The uniform weight of an animal proves that a quan- 
tity OF nitrogen must have been expelled from the system, 

EXACTLY CORRESPONDING TO THE AMOUNT CONTAINED IN THE FOOD 

CONSUMED. The compounds consisting of carbon and hydrogen, 
derived from the waste matter, are separated by the lungs and 
skin ; whilst those containing nitrogen are eliminated in the 
urine. When the body increases in weight, a smaller quantity 
of nitrogenous compounds must be separated by the urine ; a 
diminution in weight indicates, on the other hand, a greater 
separation of these compounds. These considerations prove that 
the nitrogen extracted from the atmosphere by plants as food, is 
again in a great measure returned in the urine of man and other 
animals. 

It is obvious that, by collecting both the solid and liquid excre- 
ments of an animal fed upon the produce of a certain surface of 
land, we are enabled to supply to it nearly the same quantity of 
nitrogen as that contained in the original produce. Thus we 
supply to the land a certain quantity of ammonia, in addition to 
that which may be extracted from the atmosphere by the plants 
growing upon it. 

In a scientific point of view, it should be the care of the agri- 
culturist so to employ all the substances containing a large pro- 
portion of nitrogen, which his farm affords in the form of animal 
excrements, that they shall serve as nutriment to his own plants. 
This will not be the case unless those substances are properly 
distributed upon his land. A heap of manure lying unemployed 
upon his land would serve him no more than his neighbors. The 
nitrogen in it would escape as carbonate of ammonia into the 
atmosphere, and a mere carbonaceous residue of decayed plants 
would, after some years, be found in its place. 

Tacitus informs us that the surface of Germany was in his 
time completely covered with impenetrable forests. But now 
these no longer exist, and all their constituents have disappeared. 
The carbon and nitrogen deposited in the soil in the form of 
humus and ammonia have now returned to the atmosphere. 



62 SOURCE AND ASSIMILATION OF NITROGEN. 

All putrefying animal matters emit carbonic acid and ammonia 
as long as nitrogen exists in them. In every stage of their putre- 
faction an escape of ammonia from them may be induced by 
moistening them with a potash ley ; the ammonia being apparent 
to the senses by a peculiar smell, and by the dense white vapor 
exhibited when a solid body moistened with an acid is brought 
near it. This ammonia evolved from manure is imbibed by the 
soil either in solution in water, or in the gaseous form, and plants 
thus receive a larger supply of nitrogen than is afforded to them 
by the atmosphere.* 

But it is much less the quantity of ammonia yielded to a soil 
by animal excrements, than the form in which it is presented by 
them, that causes their great influence on its fertility. Wild 
plants obtain more nitrogen from the atmosphere in the' form of 
ammonia than tliey require for their growth ; for the water 
evaporated through their leaves and blossoms emits, after some 
time, a putrid smell, a peculiarity possessed only by bodies con- 
taining nitrogen. Cultivated plants receive the same quantity of 
nitrogen fi'om the atmosphere as trees, shrubs, and other wild 

* " I filled a large retort," says Sir H. Davy, " capable of containing 
three pints of water, with some hot fermenting manure, consisting prin- 
cipally of the litter and dung of cattle ; and adapted a small receiver to 
the retort, and connected the whole with a mercurial pneumatic appa- 
ratus, so as to collect the condensible and elastic fluids which might rise 
from t.b«" dung. The receiver soon became lined with dew, and drops 
began in a few hours to trickle down the sides of it. Elastic fluid like- 
wise was generated ; in three days 35 cubical inches had been formed, 
which, when analysed, were found to contain 21 cubical inches of car- 
bonic acid ; the remainder was hydro-carbonate mixed with some azote, 
probably no more than existed in the common air in the receiver. The 
fluid matter collected in the receiver at the same time amounted to 
nearly half an ounce. It had a saline taste, and a disagreeable smell, 

nd contained some acetate and carbonate of ammonia. 
" Finding such products given off from fermenting litter, I introduced 

lie beak of another retort, filled with similar dung very hot at the 
,ime, into the soil amongst the roots of some grass in the border of a 
garden; in less than a week a very distinct effect was produced on the 
grass ; upon the spot exposed to the influence of the matter disengaged 
in fermentation, it grew with more luxuriance than the grass in any 
other part of the garden." — Works of Sir H. Davy, Edited by Dr Johc 
Davy, vol. viii., page 31 



USE OF GYPSUM. 53 



plants ; and this is quite sufficient for the purposes of agricul- 
ture. Agriculture differs essentially from the cultivation of 
forests, inasmuch as its principal object consists in the production 
of THE CONSTITUENTS OF THE BLOOD ; whilst the object of forest 
culture is confined principally to the production of carbon. But 
the presence of ammonia alone does not suffice for the production 
of the nitrogenous ingredients. Other conditions likewise are 
quite essential. All the various means of culture are sub- 
servient to these two main purposes. A part only of the car 
bonate of ammonia conveyed by rain to the soil is received by 
plants, because a certain quantity of it is volatilized with the 
vapor of water ; only that portion of it can be assimilated which 
sinks deeply into the soil, or which is conveyed directly to the 
leaves by dew, or is absorbed from the air along with the 
carbonic acid. 

Liquid animal excrements, such as the urine with which the 
solid excrements are impregnated, contain only a small part of 
their ammonia in the state of salts, that is, in a form in which it 
has completely lost its volatility. The greatest part exists in the 
form of carbonate of ammonia — a salt of great volatility. When 
the ammonia is presented in the condition of a fixed salt, not the 
smallest portion of it is lost to plants ; it is all dissolved by water, 
and imbibed by their roots. The evident influence of gypsum 
upon the growth of grasses — the striking fertility and luxuriance 
of a meadow upon which it is strewed — depends, in some degree, 
upon its fixing in the soil the ammonia of the atmosphere, which 
would otherwise be volatilized, with the water which evaporates.* 

* I made the following experiment on a small garden plot. Beans and 
peas were planted in the soil, after it had been well manured by mixing it 
with fresh horse-dung. The whole surface of the plot was strewed with 
gypsum to the depth of a line, and then covered so as to be protected from 
the rain. In dry weather it was duly watered. 

The plants soon appeared above ground and flourished with great luxuri- 
ance. Before the commencement of the experiment, I had examined both 
the soil and the gypsum, and found that both were quite free from the 
smallest trace of carbonates. But on testing some of the gypsum taken 
from the surface after the lapse of several weeks, I ascertained that the 
greatest part of it had been converted into carbonate of lime. All the 
soil to the depth of half a foot now effervesced strongly on the addition of 
acid. 



54 SOURCE AND ASSIMILATION OF NITROGEN. 



The carbonate of ammonia contained in rain-water is decomposed 
by gypsum, in precisely the same manner as in the manufacture 
of sal ammoniac. Soluble sulphate of ammonia and carbonate 
of lime are formed ; and this salt of ammonia, possessing nc 
volatility, is consequently retained in the soil. All the gypsum 
gradually disappears, but its action upon the carbonate of ammo- 
nia continues as long as a trace of it exists.* 

The beneficial influence of gypsum and of many other salts 
has been compared to that of aromatics, which increase the 
activity of the human stomach and intestines, and give a tone 
to the whole system. But plants do not contain nerves : we 
know of no substance capable of exciting them to intoxication 
and madness, or of lulling them to sleep and repose. No sub- 
stance can possibly cause their leaves to appropriate a greater 
quantity of carbon from the atmosphere, when the other constitu- 
ents required for the growth of the seeds, roots, and leaves, are 
wanting. f The favorable action of small quantities of aromatics 
upon man, when mixed with his food, is undeniable ; but aro- 
matics are given to plants without food to be digested, and still 
they flourish with greater luxuriance. 

It is quite evident, therefore, that the common view concerning 
the influence of certain salts upon the growth of plants evinces 
only ignorance of its cause. 

The action of gypsum, chloride of calcium, and of other salts 
of lime, really consists in their giving a fixed condition to the 
nitrogen, or ammonia, introduced to the soil. This nitrogen is 
indispensable for the nutrition of plants. 

In order to form a conception of the effect of gypsum, it may 
be sufficient to remark that 100 lbs. of burned gypsum fixes as 

* It has long been the practice in some parts of the country to strew 
the flooi-s of stables with gypsum. This prevents the disagreeable odcir 
arising from the putrefaction of stable manure, by decomposing and re- 
taining the ammoniacal salts. — Ed. 

" I lixivi;itpd some earth," says Spatzier, " and in the filtered solution, 
after eva|)oration, I obtained an appreciable quantity of sulphate of ammo- 
nia." — Erdmcm's Jov?-7ia/, 1S31, Bd II , s. S9. 

f Schubler states that white arsenic in small quantity exerts a beneficial 
action upon vegetation — a fact proved by Lampadius, who manured whole 
fields with this substance 



USE OF BURNED CLAY AS A MANURE. 



much ammonia in the soil as 6250 lbs. of horse's urine* would 
yield to it, even on the supposition that all the nitrogen of the 
urea and hippuric acid were absorbed by the plants without the 
smallest loss, in the form of carbonate of ammonia. If we 
furnish to a field 40 lbs. of gypsum, and if we suppose that the 
tenth part of this enters into plants in the form of sulphate of 
ammonia, we would actually supply nitrogen sufficient for 100 
lbs. of hay, 50 lbs. of wheat, or 60 lbs. of clover. 

Water is absolutely necessary to effect the decomposition of 
the gypsum, on account of its difficult solubility (1 part of gyp- 
sum requires 400 parts of water for solution), and also to assist 
in the absorption of the sulphate of ammonia by the plants : 
hence it happens, that the influence of gypsum is not observable 
on dry fields and meadows ; whi'e the gaseous carbonate of 
ammonia formed by the decay of animal manures on such fields, 
on the other hand, does not fail in producing a favorable effect. 

The decomposition of gypsum by carbonate of ammonia doe? 
not take place instantaneously ; on the contrary, it proceeds verj 
gradually ; and this explains why the action of the gypsum lasts 
for several years. 

The well-known advantage derived by manuring fields with 
burnt clay, and the fertility of ferruginous soils, may be ex- 
plained in an equally simple manner. The favorable effects 
produced by these causes have been ascribed to the great attrac- 
tion for water exerted by dry clay and ferruginous earth ; but 
common dry arable land possesses this property in as great a 
degree ; and besides, what influence can be ascribed to a hun- 
dred pounds of water spread over a field, in a condition in which 
it cannot be made available either by the roots or leaves ? The 
true cause is this : — 

Peroxide of iron and alumina are distinguished from all other 
metallic oxides by their power of forming solid compounds witii 

* The urine of the horse contains, according to Fourcroy and Vauquelin, 
in lOO) parts. 

Urea . 7 parts. 

Hippurate of soda . 14 " 

Salts and water . 979 " 



1000 parts {See Appendix.) 



96 SOURCE AND ASSIMILATION OF NITROGEN. 

ammonia. The precipitates obtained by the addition of ammonia 
to salts of" alumina or iron are true salts, in which the ammonia 
is contained as a base. Minerals containing alumina or oxide 
of iron also possess, in an eminent degree, the remarkable property 
of attracting ammonia from the atmosphere and of retaining it. 
Vauquelin, whilst engaged in the trial of a criminal case, dis- 
covered that all rust of iron contains a certain quantity of 
ammonia. Chevalier afterwards found that ammonia is a con- 
stituent of all minerals containing iron ; that even hematite, a 
mineral which is not at all porous, contains one per cent, of it. 
Bouis showed also that the peculiar odor observed on moistening 
minerals containing alumina, is partly owing to their exhaling 
ammonia. Indeed, many kinds of gypsum and some varieties 
of alumina, pipe-clay for example, emit so much ammonia, when 
moistened with caustic potash, even after they have been exposed 
for two days, that reddened litmus paper held over them becomes 
blue. Soils, therefore, containing oxides of iron, and burned 
clay, must absorb ammonia, an action which is favored by their 
porous condition ; they further prevent, by their chemical pro- 
perties, the escape of the ammonia once absorbed. Such soils, 
in fact, act precisely as a mineral acid would do, if extensively 
spread over their surface. 

The ammonia absorbed by the clay of ferruginous oxides is 
separated by every shower of rain, and conveyed in solution to 
the soil. 

Powdered charcoal possesses a similar action, but surpasses all 
other substances in the power which it possesses of condensing 
ammonia within its pores, particularly when it has been previ- 
ously heated to redness. Charcoal absorbs ninety times its 
volume of ammoniacal gas, which may be again separated by 
.simply moistening it with water. (De Saussure.) Decayed 
wood approaches very nearly to charcoal in this power ; decayed 
oak wood absorbs seventy-two times its volume of this gas, after 
liaving been completely dried under the air-pump. We have 
here an easy and satisfactory means of explaining still further 
the properties of humus, or wood in a decaying state. It is not 
only a slow and constant source of carbonic acid, but it is also 



CONCLUSION. 57 



a means by which the necessary nitrogen is conveyed to 
plants.* 

Nitrogen is found in lichens growing on basaltic rocks. Our 
fields produce more of it than we have given them as manure, 
and it exists in all kinds of soils and minerals which were never 
in contact with organic substances. The nitrogen in these cases 
could only have been extracted from the atmosphere. 

We find this nitrogen in the atmosphere, in rain-water, and in 
all kinds of soils, in the form of ammonia, as a product of the 
decay and putrefaction of preceding generations of animals and 
vegetables. We find likewise that the proportion of azotised 
matters in plants is augmented by giving them a larger supply 
of ammonia conveyed in the form of animal manure. 

No conclusion can then have a better foundation than this, 
that it is the ammonia of the atmosphere which furnishes nitro- 
gen to plants. f 

Carbonic acid, water, and ammonia, contain the elements 
necessary for the support of animals and vegetables. The same 
substances are the ultimate products of the chemical processes 
of decay and putrefaction. All the innumerable products of 
vitality resume, after death, the original form from which they 
sprung. 

Thus the destruction of an existing generation becomes the 
means for the production of a new one, and death becomes the 
source of life. 

But it may be asked — Are the compounds now named the 
only substances necessary for the support of vegetable life ? This 
question must be answered decidedly in the negative. 

* When the extract of humus is evaporated with muriatic acid, a residue 
is obtained which evolves ammonia by the addition of potash. When this 
extract is subjected to distillation along with water, and the products of 
distillation received into dilute muriatic acid, the latter is found to contain 
muriate of ammonia. Humus contains carbonate of ammonia. — Wieg- 
mann und Polsturf, Priesschrift, s. 53. 

+ We refer the reader to the Appendix for the part which nitric acid 
takes in vegetation, aad also for the origin of ammonia 



98 ON THE SOURCE OF SULPHUR. 



CHAPTER VI. 

On the Source of Sulphur. 

Physiology teaches us that all the tissues of the body, such as 
muscular fibre, cellular tissue, the organic substance of bones, 
hair, skin, &c., are formed from the blood — the fluid which cir- 
culates through every part of the organism. 

The blood, from which all parts of the animal frame are pro- 
duced, is itself furnished to animals by plants. For although 
the carnivora subsist wholly on the flesh and blood of the herbi- 
vora, they actually receive from the latter the component parts 
of the plants upon which they were nourished. 

Chemists have ascertained that sulphur is contained in the 
two principal ingredients of blood, named by them fibrin and 

ALBUMEN. 

When fresh blood is agitated with a rod or stick, fibrin is 
separated in the form of white elastic fibres. A similar separa- 
tion of this ingredient takes place when blood is allowed to stand 
for a certain time. The whole becomes coagulated into a sort of 
jelly, which gradually contracts, and separates itself into a yellow- 
ish-colored liquid, containing the serum or water of the blood, and 
into a net- work of very fine threads of fibrin. The latter inclose 
within them the coloring matter of the blood, just as a sponge 
would do in similar circumstances. 

The ALBUMEN is contained in the serum, and communicates to 
that fluid the property of coagulating by heat, in a manner 
similar to the white of an egg, which contains albumen as its 
principal ingredient. 

Fibrin, when removed from the circulation, is found to be per- 
fectly insoluble in cold water. Albumen on the other hand, in 
its natural condition, as it exists in serum or in the white of egg, 
is soluble in water, and miscible with it in all proportions. 



VEGETABLE CONSTITUENTS OF BLOOD. 59 



Casein, or cheese, the principal ingredient of milk, must also 
he enumerated as a material used in the formation of blood. 
Casein is generated in the animal economy, and is the only azo^ 
lised nutriment furnished by the mother to the young animal. 

Now albumen, fibrin, and casein contain sulphur, a circum- 
stance by which they are distinguished from all other component 
parts of the animal body. This sulphur does not exist in the 
form of an oxide, such as sulphuric acid or one of its salts. It 
is well known that the albumen of eggs emits, during its putre- 
faction, sulphuretted hydrogen gas ; and it is owing to this that 
rotten eggs possess the property of blackening silver or other 
metals with which they may be brought in contact. During the 
putrefaction of fibrin and albumen, the same gas is likewise gene- 
rated. There are many other ways by which we might prove 
the presence of sulphur in these bodies. 

From what source does the animal body derive these three fun- 
damental components ? Unquestionably they are obtained from 
the plants upon which the animals subsist : but in what form, and 
in what condition, are they contained in plants ? 

Recent investigations of chemists have enabled us to answer 
these questions with positive certainty. Plants contain, either 
deposited in their roots or seeds, or dissolved in their juices, 
variable quantities of compounds containing sulphur. In these 
nitrogen is an invariable constituent. Two of the compounds 
containing sulphur exist in the seeds of cereal plants, and in 
those of leguminous vegetables, such as peas, lentils, and beans. 
A third is always present in the juices of all plants; and it is 
found in the greatest abundance in the juices of those which we 
use for the purpose of the table. 

A very exact inquiry into the properties and composition of 
substances has produced a very remarkable result, namely, that 
the sulphur compound dissolved in the juice of plants is, in re- 
ality, identical with the albumen contained in the serum of 
blood, and in the white of an egg ; that the sulphur compound in 
the seeds of the cereals possesses the same properties and com- 
position as the fibrin of blood ; and that the nutritious constitu- 
ent of peas, beans, ar.d lentils, is actually of the same nature and 
composition as the casein of milk. Hence it follows that plants. 



60 ON THE SOURCE OF SULPHUR. 

and not animals, generate tlie constituents of blood containing 
sulphur. When these are absent from the food given to an 
animal, its blood cannot be formed. From this it also follows, 
that vegetable food will be proportionally nutritious and fit to 
sustain the vital processes of the animal body, according to the 
amount of these ingredients contained within it. 

There also exist certain families of plants, such as the Cruci- 
feree, which contain peculiar sulphur compounds much richer in 
that element than the vegetable constituents of blood. The seeds 
of black mustard, the horse-radish, garlic, onions, and scuz'vy- 
grass, are particularly marked in this respect. From all of these 
plants we obtain, by simple distillation with water, certain vola- 
tile oils, differing from all other organic compounds not contain- 
ing sulphur, by their peculiar, pungent, and disagreeable odor. 

Those compounds containing sulphur are present in the seeds 
of all plants, as well as in the plants themselves ; and as they 
are particularly abundant in cultivated plants employed for 
animal nutrition, it is quite obvious that a substance containing 
sulphur is absolutely essential to the development of such com- 
pounds, in order to supply to them their proper proportion of this 
element. 

It is also obvious, that although all other conditions for the 
nourishment of plants be present, if the compound containing 
sulphur be either wholly absent or deficient in quantity, the vege- 
table constituents containing sulphur will either be not at all 
formed, or they will be generated only in proportion to the quan- 
tity of the above compound. The air cannot contain any sub- 
stances in which sulphur is present, unless indeed we except 
minute and scarcely appreciable traces of sulphuretted hydrogen. 
The soil, therefore, must be the only means of furnishing the 
sulphur so necessary to the growth of plants ; and we are 
ignorant of any way by which it can be introduced except 
through the roots. 

The numerous analyses made of the water of mineral springs, 
furnish us with a satisfactory explanation ol' the foini in which 
sulphur occurs in soils. The water of such springs is entirely 
derived from t!ie rain which falls upon the surface' of the earth; 
the water percolating through the earth, dissolves »U *io)uble 



SUBSTANCES YIELDING SULPHUR. 61 

materials which it may meet in its course. The substances 
thus dissolved communicate to the water properties which are 
not possessed by pure water. Water procured from springs or 
wells is found to be very rarely deficient in soluble salts oi^ sul- 
phuric acid. The liquid obtained by lixiviating good soil from 
garden or arable land also contains very appreciable quantities 
of these salts. 

The facts now detailed leave little doubt as to the source 
whence plants obtain their sulphur. As far as our knowledge 
extends, they receive their sulphur from the sulphates dissolved 
in the water absorbed by their roots from the soil. 

Ammoniacal salts, particularly sulphate of ammonia, are 
rarely detected in spring water ; but this is owing to the con- 
stant presence of supercarbonate of lime, which effects their 
decomposition, and allows the escape of ammonia during the 
evaporation of the liquid for the purposes of analysis. 

According to our view, sulphate of ammonia is of all com- 
pounds containing sulphur the one most fitted for the assimilation 
of that element. Sulphate of ammonia contains two elements, 
both of which are equally necessary for the support of vegetable 
life ; these are sulphur and nitrogen, and they form constituents 
also of vegetable albumen, fibrin, and casein. But what is still 
more worthy of observation, sulphate of ammonia, viewing it 
according to the proportion of its elements, or what is termed its 
empirical formula (S O , , N H3 ,), may be considered as a com- 
pound of water with equal equivalents of sulphur and nitrogen. 
Thus, by the simple removal of the elements of water from this 
compound, its sulphur and nitrogen might be enabled to pass over 
into the composition of the plants. 

The ingredients of plants containing sulphur are so composed 
that one equivalent of sulphur exists for every 25 equivalents 
of nitrogen. Hence it is obvious that much more ammonia 
must be offered to plants than that contained in the form of sul- 
phate of ammonia, if all the sulphur of the latter is to become a 
constituent of the organic ingredients alluded to. 

This bears a complete analogy to the assimilation of the car- 
bon and nitrogen furnished to plants in the form of carbonate of 
ammonia. This salt may contain two equivalents of carbon to 



«2 ON THE SOURCE OF SULPHUR. 

one equivalent of nitrogen. Hence it is necessary that the car. 
bon of six equivalents of carbonic acid must at the same time be 
taken up, and enter into combination vv^ith the nitrogen, in order 
to produce the principal nitrogenous constituents which contain 
one equivalent of nitrogen to eight equivalents of carbon. 

The passage of sulphur derived from a sulphate into the com- 
position of vegetable matter, necessarily indicates that the sul- 
phate has been exposed to the action of the same causes as those 
by which the decomposition of carbonic acid was effected in the 
plant ; and, therefore, that the sulphuric acid has been decom- 
posed into sulphur and oxygen, the former of which is assimi- 
lated, whilst the latter is separated. If we suppose the sulphuric 
acid to be presented in the form of sulphate of potash or soda, the 
bases of these salts must be set at liberty after the decomposition 
of their acid. 

Now we actually find these bases in all cultivated, and even 
in most wild plants. They are found either united to organic 
acids, or, what is still more remarkable, they are found in union 
with the vegetable conipounds containing sulphur. The vege- 
table casein of peas, beans, and other leguminous plants, is itself 
insoluble in water; but it is very soluble in the form in which 
it occurs in the plant. This solubility is due to the soda and 
potash with which it is united. In like manner, the albumen 
contained in the juices of plants is combined with an alkali ; and 
we must suppose that vegetable fibrin, the insoluble ingredient of 
cereal plants, must have originally been soluble, and have at- 
tained its position in the seeds by the agency of alkalies. 

The potash and soda of the alkaline sulphates which furnish to 
plants their sulphur, remain, therefore, either in combination 
with the ingredients containing that element, or they enter into 
some new state of combination, or, finally, they are returned to 
the soil. 

Gypsum (sulphate of lime) is the most generally diffused sul- 
phate. Being soluble, it may either pass directly into the plant, 
or it may be decomposed by the carbonate of ammonia existing 
in rain-water, when its sulphur will pass into the plant in the 
form of sulphate of ammonia. 

A solution of gypsum contaming common salt or chloride 



MIXTURE OF GYPSUM AND OF SALT. 63 

of potassium, such as sea-water, and the water of most springs, 
may be viewed as a mixture of an alkaline sulphate with 
chloride of calcium. From this it must be obvious, that when 
we furnish to a plant at the same time both gypsum and common 
salt (chloride of sodium), we actually furnish by such a solution 
the same materials that we would do if we supplied a mixture 
of sulphate of soda and chloride of calcium. In order to form 
the constituents containing sulphur, that element and the alkali 
must be retained by the plant, while the chlorine and calcium 
will be expelled by the roots. 

We know that this process actually does take place in the 
case of marine plants. The soda or potash is obtained fron 
common salt or chloride of potassium, which suffers decomposi- 
tion by the presence of sulphate of lime or sulphate of magnesia. 
It is necessary to suppose that this process also occurs with the 
cereal and all other plants, the ashes of which are destitute of 
lime, and the sulphur of which has been supplied in the form of 
gypsum. Thus we are enabled to explain the use of common 
salt as a manure ; it enables the plant, for which this manure is 
useful, to extract its sulphur from the soil in which it existed in 
the form of sulphate of lime. 



fti OF THE INORGANIC CONSTITUENTS OF PLANTS. 



CHAPTER VII. 

Of the Inorganic Constituents of Plants.* 

Carbonic acid, water, ammonia, and sulphates, are necessary 
for the existence of plants, because they contain the elements 
from which their organs are formed ; but other substances are 
likewise requisite for the formation of certain organs destined 
for special functions peculiar to each family of plants. Plants 
obtain these substances, as they do the sulphur they contain, 
from inorganic nature. In the ashes left after the incineration 
of plants, the same substances are found, although in a changed 
condition. 

Many of the inorganic constituents vary according to the soil 
in which the plants grow, but a certain number of them are in- 
dispensable to their development. All substances in solution in 
a soil are absorbed by the roots of plants, exactly as a sponge 
imbibes a liquid, and all that it contains, without selection. The 
substances thus conveyed to plants are retained in greater or 
less quantity, or are entirely separated wh^ not suited for 
assimilation. 

Alkaline and earthy phosphates form invariable constituents 
of the seeds of all kinds of grasses, of beans, peas, and lentils. 

These salts are introduced into bread along with the flour, and 

* " Many authors," says Saussure, " consider that the mineral ingredi- 
ents of plants are merely accidentally present, and are not at all necessary 
to their existence, because the quantity of such substances is exceedingly 
small. This opinion may be true as far as regards those matters whicli 
are not always found in plants of the same kind ; but there is certainly no 
evidence of its truth with those invariably present. Tlieir small quantity 
does not indicate their inutility. The phosphate of lime existing in the 
animal body does not amount to the fifth part of its weight, yet no one 
doubts that this salt is necessary for the formation of its bones. I have 
detected the same compound in the ashes of all plants submitted to exami- 
nation, and we have no right to suppose that they could exist without it." 
(De Saiissnre, p. 241.) 



IMPORTANCE OF ALKALINE BASES. - 65 

into beei* along with barley. The bran of flour contains a large 
quantity of ammoniacal phosphate of magnesia. This salt forms 
large crystalline concretions, often amounting to several pounds 
in weight, in the ccBcum of horses belonging to millers ; and 
when ammonia is mixed with beer, the same salt separates as a 
white precipitate. 

Most plants, perhaps all of them, contain organic acids of very 
different composition and properties, all of which are in combina- 
tion with bases, such as potash, soda, lime, or magnesia ; plants 
containing free organic acids are few in number. These bases 
evidently regulate the formation of the acids, for the diminution 
of the one is followed by a decrease of the other : thus in the 
grape, for example, the quantity of acid contained in its juice is 
less when it is ripe than when unripe ; and the bases, under the 
same circumstances, are found to vary in a similar manner. 
Such constituents exist in the smallest quantity in those parts of 
a plant in which the process of assimilation is most active, as in 
the mass of woody fibre ; and their quantity is greatest in those 
organs whose ofiice it is to prepare substances conveyed to them 
for assimilation by other parts. The leaves contain more inor- 
ganic matters than the branches, and the branches more than the 
stem (Saussctre). The potatoe plant contains more potash before 
blossoming than after it (Mollerat). 

The acids found in the different families of plants are of vari- 
ous kinds ; it cannot be supposed that their presence and peculi- 
arities are the result of accident. The fumaric and oxalic acids 
in the lichens, the kinic acid in the RubiacecB, the rocellic acid 
in the Rocella tinctoria, the tartaric acid in grapes, and the nu- 
merous other organic acids, must serve some end in vegetable 
life. But if these acids constantly exist in vegetables, and are 
necessary to their life, which is incontestable, it is equally cer- 
tain that some alkaline base is also indispensable, in order to enter 
into combination with the acids ; for these are always found in 
the state of neutral or acid salts. All plants yield by incinciration 
ashfcs containing carbonic acid ; all, therefore, must contain salts 
of an organic acid.* 

* Salts of organic acids yield carbonates on incineration, if they contaio 
either alkaline or earthy bases. 



«6 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

Now, as we know the capacity of saturation of organic acids 
to be unchanging, it follows that the cuantity of the bases united 
with them cannot vary ; and for this reason the latter substances 
ought to be considered with the strictest attention, both by the 
agriculturist and physiologist. 

We have no reason to believe that a plant in a condition of 
flee and unimpeded growth produces more of its peculiar acids 
than it requires for its own existence ; hence, a plant, on what- 
ever soil it grows, must contain an invariable quantity of alkaline 
bases. Culture alone will be able to cause a deviation. 

In order to understand this subject clearly, it will be necessary 
to bear in mind that any one of many of the alkaline bases may 
be substituted for another, the action of all being the same. Our 
conclusion is, therefore, by no means endangered by the exist- 
ence in one plant of a particular alkali which may be absent in 
others of the same species. If this inference be correct, the 
absent alkali or earth must be supplied by one similar in its mode 
of action, or in other words, by an equivalent of another base. 
The number of equivalents of these various bases which may be 
combined with the acid in a given plant must consequently be a 
constant quantity, and therefore the amount of oxygen contained 
in them must remain unchanged under all circumstances and on 
whatever soil they grow.* 

* When sulphuric acid is placed in contact with potash, soda, lime, or 
magnesia, the properties both of the acid and of the alkali disappear, and 
if the proportions have been just, the compound thus produced is a neutral 
sulphate of these bases. 

100 parts of sulphuric acid require for neutralization very difterent quanti- 
ties of the above bases ; thus, to effect this purpose, it is necessary to em- 
ploy 118 parts of potash, 78 parts of soda, 71 "2 parts of lime, and Sl'G parts 
of magnesia. 

In order to produce a neutral nitrate with IIS parts of potash (the quan- 
tity necessary to saturate 100 parts of sulphuric acid), we must employ 135 
parts of nitric acid. Now, when we examine how much soda, lime, or 
magnesia is required to saturate the same quantity of nitric acid (135 parts) 
it is found that complete saturation is effected by 78 of soda, 7r2 of lime, 
51 •(5 of magnesia, or exactly the same quantities as in the case of sulphuric 
acid. It is quite indifferent what acids we use to neutralize their bases, or 
how much the numbers obtained may differ from those now stated ; still 
the relative proportion remains invariable. If for the saturation of anj 



INVARIABLE QUANTITY OF ALKALINE BASES. 



6' 



Of course, this argument refers only to those alkaline bases 
which in the form of organic salts form constituents of the plants. 
Now, these salts are preserved in the ashes of plants as carbon- 
ates, the quantity of which can be easily ascertained. The 
bases contained in the bark do not any longer belong to the vital 
organism of the plant. 

It has been distinctly shown, by the analyses of De Saussure 
and Berthier, that the nature of a soil exercises a decided influ- 
ence on the quantity of the different metallic oxides contained in 
the plants which grow on it ; that magnesia, for example, was 
contained in the ashes of a pine-tree grown at Mont Breven, 



particular acid 51 "6 parts of magnesia have been used, we may be perfectly 
certain that the same quantity of this acid will be exactly neutralized by 
7S parts of soda. 

We have now to state the causes which occasion this unequal power of 
these metallic oxides to neutralize acids We have also to explain why, to 
produce the same effect, it is necessary to employ a smaller quantity of soda, 
and only one half the quantity of magnesia that we would use of potash, 
and still that the relative quantities are constant with all acids. 

A knowledge of the composition of the bases has afforded us a very sim 
pie explanation of these causes. All the bases now mentioned contain 
oxygen combined with a metal ; and their capacity of saturation depends 
upon the quantity of oxygen contained within them. 

Although the absolute quantities of the above bases are so very different, 
they all contain the same quantities of oxygen. 

Oxygen contained. 
100 Sulphuric Acid neutralize 118 Potash = 20 
100 " " " 78 Soda = 20 

100 " " " 71-2 Lime = 20 

100 " " " 51-6 Magnesia = 20 

Now, if we neutralize 100 parts of sulphuric acid with potash and soda, 
or with potash, soda, and lime, or with potash, soda, lime, and magnesia, 
the sulphuric acid unites with quantities of two, three, or four bases exactly 
corresponding to their united quantity of oxygen. This may be represent- 
ed in the following table : — 



100 parts sulphuric acid neutralize ) o ^i- ( 20 parts oxygen 



100 



100 



Potassium 
dium 

C Potassium ^ 

< Sodium > 

( Calcium J 

[ Potassium "j 

I Sodium i 

1 Calcium j 

^ Magnesium J 



20 



20 



oxygen. 



oxygen. 



88 OF THE INORGANIC CONSTITUENTS OF PLANTS 

whilst it was absent from the ashes of a tree of the same speciea 
from Mont La Salle, and that the proportion of lime and potash 
was also very different. 

Hence it has been concluded (erroneously, I believe), that the 
presence of bases exercises no particular influence upon the 
growth of plants : but even were this view correct, it must be 
considered as a most remarkable accident that these same analyses 
furnish proof for the very opposite opinion. For although the 
composition of the ashes of these pine-trees was so very different, 
they contained, according to the analyses of De Saussure, an 
equal number of equivalents of metallic oxides ; or, what is the 
same thing, the quantity of oxygen contained in all the bases was 
in both cases the same. 

100 parts of the ashes of the pine-tree from Mont Breven con- 
tained — 

Carbonate of Potash . 3'60 Quantity of oxygen in the Potash .0-415 
" Lime . 46-34 " '^ " Lime . 7-3-27 

" Magnesia 6-77 " " " Magnesia. 1"265 

Sum of the carbonates 56-71 Sum of the oxygen in the bases 9-007 

100 parts of the ashes of the pine from Mont La Salle con- 
tained — * 

Carbonate of Potash . 7-35 Quantity of oxygen in the Potash . 0-85 
" Lime . 51-19 " " " Lime . 8-10 

" Magnesia 00-00 

Sum of the carbonates 58-55 Sum of the oxygen in the bases S-95 

The numbers 9*007 and 8*95 approach each other as nearly 
as could be expected even in analyses made for the very purpose 
of ascertaining the fact above demonstrated ; which the analyst 
in this case had not in view. 

Let us now compare Berthier's analyses of the ashes of two 
fir-trees, one of which grew in Norway, the other in Allevard 
(departement de I'lsdre). One contained 50, the other 25 per 

* According to the experiments of Saussure, 1000 parts of the wood of 
the pine from Mont Breven gave 11-87 parts of ashes; the same quantitj 
of wood fronc Mont La Salle yielded 11-28 parts. 




INVARIABLE QUANTITY OF ALKALINE BASES. 69 

cent of soluble salts. A greater difference in the proportion of 
the alkaline bases could scarcely exist between two totally dif- 
ferent plants, and yet even here the quantity of oxygen in the 
bases of both was the same. 

loo parts of the ashes of firwood from AUevard contained, 
according to Berthier (Ann. de Chim. et de Phys., t. xxxii., 
p. 248), 

Potash and Soda 16'8 in which 3"57 parts must be oxygen ' 
Lime . . 29-6 " 8-36 " " 

Magnesia . 3-3 " 1-26 " jf 



49-7 13-19 ^ 

Only part of the potash and soda in these ashes was in com- 
bination with organic acids ; the remainder was in the form of 
sulphates, phosphates, and chlorides. One hundred parts of 
the ashes contain 0-797 sulphuric acid, 3'12 phosphoric acid, 
and 0-077 hydrochloric acid, which together neutralize a quan- 
tity of base containing 0-53 oxygen. This number, therefore, 
must be subtracted from 13'19. The remainder, 12-66, indi- 
cates the quantity of oxygen in the alkaline bases, combined 
with organic acids in the firwood of Allevard. 

The firwood of Norway contained in 100 parts, — 

14-1 of which 2-4 parts would be oxygen. 
5-3 

3-82 " " 

1-69 " * 

52-75 13-21 

And if we subtract from 13-21 the quantity of oxygen of the 
bases in combination with sulphuric and phosphoric acid, viz., 
0-79, 12-42 parts remain as the amount of oxygen contained in 
the bases which were in combination with organic acids. 

These remarkable approximations cannot be accidental ; and 
if future investigations confirm them in other kinds of plants, no 
other explanation than that already given can be adopted. 

It is not known in what form manganese, and oxide of iron, 
ere contained in plants ; bu^ we are certain that potash, soda, 



Potash . 


. 14-1 


Soda 


. 20-7 


Lime 


. 13-6 


Magnesia 


. 4-35 



70 OF THE INORGANIC CONSTITUENTS OF PLANTS. 



and magnesia, can be extracted by means of water from all parts 
of their structure in the form of salts of organic acids. The 
same is the case with lime, when not present as insoluble oxalate 
of lime. It must here be remembered, that in plants yielding 
oxalic acid, the acid and potash never exist in the form of the 
neutral oxalate or quadroxalate, but always as a binoxalate, on 
whatever soil they may grow. The potash in grapes is always 
found as an acid salt, viz., cream of tartar (bitartrate of potash), 
and never in the form of a neutral compound. As these acids 
and bases are never absent from plants, and as even the form in 
which they present themselves is not subject to change, it may 
be affirmed that they exercise an important influence on the 
development of the fruits and seeds, and also on many other 
functions, of the nature of which we are at present ignorant. 
The quantity of alkaline bases existing in a plant also depends 
evidently on this circumstance of their existing only in the form 
of salts of certain acids, — for the capacity of saturation of an acid 
is constant. 

From these considerations we must perceive, that exact and 
trustworthy examinations of the ashes of plants of the same 
kind growing upon different soils would be of the greatest im- 
portance to vegetable physiology, and would decide whether the 
facts above mentioned are the results of an unchanging law for 
each family of plants, and whether an invariable number can be. 
found to express the quantity of oxygen which each species of 
plant contains in the bases united with organic acids. In all pro- 
bability such inquiries will lead to most important results ; for it 
is clear that if the production of a certain unchanging quantity 
of an organic acid is required by the peculiar nature of the 
organs of a plant, and is necessary to its existence, then potash 
or lime must be taken up by it in order to form salts with this 
acid ; that if these do not exist in sufficient quantity in the soil, 
other alkaline bases, of equal value, must supply their place ; 
and that the progress of a plant must be wholly arrested when 
none are present. 

Seeds of the Salsola kali, when sown in common garden soil, 
produce a plant containing both potash and soda ; while the plants 



SUBSTITUTION OF ALKALINE BASES. 71 

grown from the seeds of this contain only salts of potash, with 
mere traces of muriate of soda.* (Cadet.) 

The existence of vegetable alkalies in combination with organic 
acids gives great weight to the opinion that alkaline bases in 
general are connected with the development of plants. 

If potatoes are grown where they are not supplied with earth, 
the magazine of inorganic bases (in cellars, for example), a true 
alkali, called Solanin, of very poisonous nature, is formed in the 
sprouts extending towards the light, while mere traces of such a 
substance can be discovered in the roots, herbs, blossoms, or fi*^ 
of potatoes grown in fields (Otto). In all the species off 
Cinchona, kinic acid is found ; but the quantity of quinina, cih- 
chonina, and lime contained in them is most variable. From the 
fixed bases in the products of incineration, however, we may esti- 
mate pretty accurately the quantity of the peculiar organic bases. 
A maximum of the first corresponds to a minimum of the latter, 
as must necessarily be the case if they mutually replace one 
another according to their equivalents. We know that different 
kinds of opium contain meconic acid in combination with very 
diiferent quantities of narcotina, morphia, codeia, &c., the quan- 
tity of one of these alkaloids diminishing on the increase of the 
others. Thus the smallest quantity of morphia is accompanied 
by a maximum of narcotina. Not a trace of meconic acidf can 
be discovered in many kinds of opium, but there is not on this 

* " We planted," says Wiegmann and Polstorf, " several plants in a 
flower-pot filled with common earth from the garden, and watered them 
with a weak solution of chloride of potassium, having previously ascer- 
tained that the earth contained mere traces of metallic chlorides. Sub- 
jected to this treatment, the plants flourished very luxuriantly, so much 
so that they completely covered the flower-pot, stretching far over its 
sides. We now transplanted them into the open soil, and did not supply 
them any longer with chloride of potassium ; but, in the following year, 
they shrunk and died during the period of blossoming. It follows, from 
the experiments which we have detailed, that both kinds of plants re- 
quired metallic chlorides for their proper nourishment, but that it is quit? 
indifferent whether the chlorine be united with sodium or potassium." 
(Preischrift uber die anorgaiiischen Bestandtheile dcr PJla?ize7i.) 

t Robiquet did not obtain a trace of meconate of lime from 309 lbs 
of opium, whilst in other kinds the quantity was very considerabl* 
{■Ann. dp. Chim , liii., p 425) 



4 

72 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

account an absence of acid, for the meconic is here replaced by 
sulphuric acid. Here, also, we have an example of what has 
been before stated ; for in those kinds of opium where both these 
acids exist, they are always found to bear a certain relative pro- 
portion to one another. 

Now if it be found, as appears to be the case in the juice of 
poppies, that an organic acid may be replaced by an inorganic 
without impeding the growth of a plant, we must admit the pro- 
bability of this substitution taking place in a much higher degree 
in the case of the inorganic bases. 

When roots find their more appropriate base in sufficient 
quantity, they will take up less of another. 
'""These phenomena will not show themselves so frequently in 
cultivated plants, because they are subjected to special external 
conditions, for the purpose of the production of particular con- 
stituents or of particular organs. 

By sprinkling with the juice of the Phytolacca decandra, the 
soil in which a white hyacinth is growing in a state of blossom, 
its white blossoms assume in one or two hours a red color, which 
again disappears after a kw days under the influence of sunshine, 
and they become white and colorless as before.* The juice in 
this case evidently enters into all parts of the plant, without 
being at all changed in its chemical nature, or without its 
presence being apparently either necessary or injurious. But 
this condition is not permanent, and when the blossoms have 
again become colorless, none of the coloring matter remains ; 
and if it should occur that any of its elements were adapted for 
the purposes of nutrition of the plant, then these alone would be 
retained, whilst the rest would be excreted in an altered form by 
the roots. 

Exactly the same thing must happen when we sprinkle a plant 
with a solution of chloride of potassium, nitre, or nitrate of 
strontia ; they will enter into the different parts of the plant, just 
as the colored juice mentioned above, and will be found in its 
ashes if it should be burnt at this period. Their presence is 

* Biot, in the Comptes rendus des S^nnces de I'Acad^mie des Sciences, 
a Paris, premier Semestre, 1837, p. 12. 



EXCREMENTS OF PLANTS. 73 

merely accidental ; but this does not furnish ground for any con- 
clusion against the necessity of the presence of other bases in 
plants. The experiments of Macaire-Princep have shown, that 
plants made to vegetate with their roots in a weak solution of 
acetate of lead, and then in rain-water, yield to the latter all the 
salt of lead which they had previously absorbed. They return, 
therefore, to the soil all matters unnecessary to their existence. 
Again, when a plant, freely exposed to the atmosphere, rain and 
sunshine, is sprinkled with a solution of nitrate of strontia, the 
salt is absorbed, but it is again separated by the roots and 
removed further from them by every shower of rain that falls 
upon the soil, so that at last not a trace of it is to be found in the , 
plant. (Daubeny.) Let us consider the composition of the 
ashes of the two fir-trees above mentioned as analysed by an 
acute and most accurate chemist. One of these grew in Nor- 
way, on a soil of invariable composition, but to which soluble 
salts, and particularly common salt, were conveyed in great 
quantity by rain-water. How did it happen that its ashes con- 
tained no appreciable trace of salt, although we are certain that 
its roots must have absorbed it after every shower ? 

We can explain the absence of salt in this case by means i 
of the direct and positive observations referred to, which have 1 
shown that plants have the power of returning to the soil all ' 
substances unnecessary to their existence ; and the conclusion to 
which all the foregoing facts lead us, when their real value and 
bearing are apprehended, is that the alkaline bases existing in 
the ashes of plants must be necessary to their growth, since if 
this were not the case they would not be retained. 

The perfect development of a plant, according to this view, is 
dependent on the presence of alkalies or of alkaline earths ; for 
when these substances are totally wanting its growth will be ar- 
rested, and when they are only deficient it must be impeded. 

In order to apply these remarks, let us compare two kinds of 
trees, the wood of which contains unequal quantities of alkaline 
bases, and we shall find that one of these may grow luxuriantly 
in several soils upon which the other is scarcely able to vegetate. 
For example, 10,000 parts of oak-wood yield 250 parts of ashes, 



74 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

the same quantity of fir-wood only 83, of lime-wood 500, of rye 
440, and of the herb of the potatoe plant 1500 parts.* 

Firs and pines find a sufficient quantity of alkalies in granitic 
and barren sandy soils in which oaks will not grow ; and wheat 
thrives in soils favorable for the lime-tree, because the bases 
necessary to bring it to complete maturity exist there in suffi- 
cient quantity. The accuracy of these conclusions, so highly 
important to agriculture and to the cultivation of forests, can be 
proved by the most evident facts. 

All kinds of grasses, and the EquisetacecB, for example, con- 
tain in the outer parts of their leaves and stalk, a large quantity 
of silicic acid and potash in the form of acid silicate of potash. The 
proportion of this salt does not vary perceptibly in the soil of 
corn-fields, if it be again conveyed to them as manure in the form 
of putrefying straw. But this is not the case in a meadow, and 
hence we never find a luxuriant crop of grass j" on sandy and cal- 
careous soils containing little potash, evidently because one of the 
cor.stituents indispensable to the growth of the plants is wanting. 
Soils formed from basalt, grauwacke, and porphyry, are, ceteris 
paribus, the best for meadow-land, on account of the large quan- 
tity of potash they contain. The potash abstracted by the 
plants is restored during the annual irrigation. The amount of 
alkalies contained in the' soil itself is very great in com- 
parison with the quantity removed by plants, although not 
inexhaustible. 

A harvest of grain is obtained every thirty or forty years 
from the soil of the Luneburg heath by strewing it with the 
ashes of the heath-plants (Erica vulgaris) growing upon it. 
These plants, during the long period just mentioned, collect the 
potash and soda contained in the soil and conveyed to them by 
rain-water ;- and it is by means of these alkalies that oats, barley, 
and rye, to which they are indispensable, are enabled to grow on 
this sandy heath. 

* Berthier, Annales de Chimie et de Physique, t. xxx., p. 248. 

t It would be of importance to examine what alkalies are contained in 
the ashes of the sea-shore plants which grow in the humid hollows of 
downs, and especially those of the millet-grass If potash is not found in 
them, it must certainly be replaced by soda, as in the Salsola, or by lime, 
u in the PlumbaginetB. 



REPLACEMENT OF EXHAUSTED ALKALIES. -5 

The woodcutters in the vicinity of Heidelberg have the privi- 
lege of cultivating the soil for their own use, after felling the 
trees used for making tan. Before sowing the land thus obtained, 
the branches, roots, and leaves, are in every case burned, and 
the ashes used as a manure, which is found to be quite indispen- 
sable for the growth of the grain. The soil itself upon which 
the oaks grow in this district consists of sandstone ; and although 
the trees find in it a quantity of alkaline earths sufficient for 
their own sustenance, yet in its ordinary condition it is incapable 
of producing cereal crops. 

The most decisive proof of the use of strong manure was ob- 
tained at Bingen (a town on the Rhine), where the produce and 
development of vines were highly increased by manuring them 
with such nitrogenous manures as shavings of horn, &c. ; but 
after some years the formation of the wood and leaves decreased 
to the great loss of the proprietor, to such a degree that he has 
long had cause to regret his departure from the usual methods, 
ascertained by long experience to be the best. By the manure 
employed by him, the vines had been too much hastened in their 
growth ,• in two or three years they had exhausted the potash in 
the formation of their fruit, leaves, and wood, so that none re- 
mained for the future crops, his manure not having contained 
any potash. 

There are vineyards on the Rhine, the plants of which are 
above a hundred years old, and all of these have been cultivated 
by manuring them with cow-dung, a manure containing a large 
proportion of alkaline ingredients, although very littlfe nitrogen. 
All the alkalies, in fact, contained in the food consumed by a 
cow are again immediately discharged in the liquid excrements. 

The leaves and small branches of trees contain the greatest 
quantity of ashes and of alkalies ; and the quantity of them annu- 
ally removed from a wood, for the purpose of being employed as 
litter,* contain much more of the alkalies than all the old wood 

* [This refers to a custom some time since very prevalent in Germany, 
although now discontinued. The leaves and small twigs of trees were 
gleaned from the forests by poor people, for the purpose of being used as 
litter for their cattle. The trees, hov\'ever, were found to suffer so much 
in consequence, that their removal is now strictly prohibited. The cause 
of the injury was that stated in the text. — Ed.] 



76 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

cut down. The bark and foliage of oaks, for example, contain 
from 6 to 9 per cent, of alkalies, the needles of firs and pines, 8 
per ceLt. 

With every 2650 lbs. of firwood yearly removed from an acre 
of forest, only 7 or 8 lbs. of alkalies are abstracted from the soil, 
calculating the ashes at 0.83 per cent. The leaves, however, 
cover the soil, and being very rich in alkalies, in comparison 
with the wood, retain those alkalies on the surface, which would 
otherwise so easily penetrate with the rain through the sandy 
soil. By their decay an abundant provision of alkalies is sup- 
plied to the roots of the trees, and a fresh supply is rendered 
unnecessary. 

The ashes of the tobacco plant, of the vine, of peas, and of 
clover, contain a large quantity of lime. Such plants do not 
flourish on soils devoid of lime. By the addition of salts of lime 
to such soils, they become fitted for the growth of these plants ; 
for we have every reason to believe that their development es- 
sentially depends upon the presence of lime. The presence of 
magnesia is equally essential, there being many plants, such as 
the different varieties of beet and potatoes, from which it is never 
absent. 

The supposition that alkalies, metallic oxides, or inorganic mat- 
ter in general, are produced by plants, is entirely refuted by 
these well-authenticated facts. 

It is thought very remarkable, that the plants of the grass 
tribe, fitted for the food of man, follow him like the domestic 
animals. But saline plants seek the sea-shore or saline springs, 
and the Chenopodium the dunghill, from similar causes. Saline 
plants require common salt, and the plants growing only on dung- 
hills need ammonia and nitrates, and they are attracted to places 
where these can be found, just as the dung-fly is to animal ex- 
crements. So likewise none of our corn plants can bear perfect 
seeds, that is, seeds yielding flour, without a large supply of 
phosphate of magnesia and ammonia, substances which they re- 
quire for their maturity. And hence, these plants grow only in 
a soil where these three constituents are found combined, and no 
soil is richer in them than those where men and animals dwell 
together ; where the urine and excrements of these are found 



NECESSITY OF CERTAIN CONDITIONS FOR NUTRITION. 77 

corn plants appear, because their seeds cannot attain maturity 
unless supplied with the constituents of those matters. 

When we find sea plants near our salt-works, several hundred 
miles distant from the sea, we know that their seeds have been 
carried there in a very natural manner, namely, by wind or by 
birds, which have spread them over the whole surface of the 
earth, although they grow only in those places in which they find 
the conditions essential to their life. 

Numerous small fish, of not more than two inches in length 
(Gasferosteus aculeatus), are found in the salt-pans of the gradu 
ating-house at Nidda (a village in Hesse Darmstadt). No livinj; 
animal is found in the salt-pans of Neuheim, situated about lb 
miles from Nidda ; but the water there contains so much car- 
bonic acid and lime, that the walls of the graduating-house are 
covered with stalactites. Hence the eggs conveyed to this place, 
by whatever cause, do not find the conditions necessary for their 
development, although they did so in the former place. 

How much more wonderful and inexplicable does it appear, 
that bodies, remaining fixed in the strong heat of a fire, have un- 
der certain conditions the property of volatilizing and, at ordinary 
temperatures, of passing into a state, of which we cannot say 
whether they have really assumed the form of a gas or are dis- 
solved in one ! Steam or vapors in general have a very singu- 
lar influence in causing the volatilization of such bodies, that is 
of causing them to assume the gaseous form. A liquid during 
evaporation communicates the power of assuming the same state 
in a greater or lesn degree to all substances dissolved in it, 
although they do not of themselves possess that property. 

Boracic acid is a perfectly fixed substance ; it suffers no 
change of weight appreciable by the most delicate balance, when 
exposed to a white heat, and therefore it is not volatile. Yet its 
solution in water cannot be evaporated by the gentlest heat, with 
out the escape of a sensible quantity of the acid with the steam. 
Hence it is that a loss is always experienced in the analysis of 
minerals containmg this acid, when liquids in which it is dissolved 
are evaporated. The quantity of boracic acid which escapes 
with a cubic foot of steam, at the temperature of boiling water, 
cannot be detected by our most sensible re-agents; but nevertho 



78 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

less the many hundred tons annually brought from Italy as an 
article of commerce, are procured by the uninterrupted accu- 
mulation of this apparently inappreciable quantity. The hot 
steam issuing from the interior of the earth, passes through cold 
water in the lagoons of Castel Nuovo and Cherchiago ; in this 
way the boracic acid is gradually accumulated, till at last it may 
be obtained in crystals by the evaporation of the water. It is 
evident, from the temperature of the steam, that it must have 
come out of depths in which human beings and animals never 
could have lived, and yet it is very remarkable and highly 
important that ammonia is never absent from it. In the large 
works in Liverpool, where natural boracic acid is converted into 
borax, many hundred pounds of sulphate of ammonia are obtained 
at the same time. 

This ammonia has not been produced by the animai or- 
ganism, BUT existed before THE CREATION OF HUMAN BEINGS, 
BEING A PART, A PRIMARY CONSTITUENT, OF THE GLOBE ITSELF. 

The experiments instituted under Lavoisier's guidance by the 
Direction des Poudres et Salpetres, have proved that during the 
evaporation of the saltpetre ley, the salt volatilizes with the water, 
and causes a loss which could not before be explained. It is 
known also that, in sea-storms, leaves of plants in the direction 
of the wind are covered with crystals of salt, even at the dis- 
tance of from 20 to 30 miles from the sea. But it does not 
require a storm to cause the volatilization of the salt, for the air 
hanging over the sea always contains enough of this substance 
to render turbid a solution of nitrate of silver, and every breeze 
must carry this away. Now, as thousands of tons of sea-water 
annually evaporate into the atmosphere, a corresponding quantity 
of the salts dissolved in it, viz., of common salt, chloride of potas- 
sium, magnesia, and the remaining constituents of the sea-water, 
will be conveyed by wind to the land. 

This volatilization is a source of considerable loss in salt- 
works, especially where the proportion of salt in the water is 
small. This has been completely proved at the salt-works of 
Nauheim, by the very intelligent director of that establishment, 
M. Wilhelmi. He hung a plate of glass between two evaporat- 
ing houses, distant about 1200 paces from each other, and found 



INORGANIC ORIGIN OF AMMONIA. 79 

.n the morning, after the drying of the dew, that the glass was 
covered with crystals of salt on one or the other side, according 
to the direction of the wind. 

By the continual evaporation of the sea, its salts* are spread 
over the whole surface of the earth ; and being subsequently 
carried down by the rain, furnish to vegetation those salts neces- 
sary to its existence. This is the origin of the salts found in the 
ashes of plants, in those cases where the soil could not have 
yielded them. 

In a comprehensive view of the phenomena of nature, we have 
no scale for that which we are accustomed to name small or 
great ; all our ideas are proportioned to what we see around us ; 
but how insignificant are they in comparison with the whole 
mass of the globe ! that which is scarcely observable in a con- 
fined district appears inconceivably large when regarded in its 
extension through unlimited space. The atmosphere contains 
only a thousandth part of its weight of carbonic acid ; and yet 
small as this proportion appears, it is quite sufficient to supply 
the whole of the present generation of living beings with car- 
bon for thousands of years, even if it were not renewed. Sea- 
water contains t^ ^pg of its weight of carbonate of lime ; and 
Ibis quantity, although scarcely appreciable in a pound, is the 

* According to Marcet, sea-water contains in 1000 parts, 
26-660 Chloride of Sodium. 
4-660 Sulphate of Soda. 
1-232 Chloride of Potassium. 
5-152 Chloride of Magnesium. 
1-5 Sulphate of Lime. 



39-204 
According to Clemm, the water of the North Sea contains in 1000 parte, 
24-84 Chloride of Sodium. 
2-42 Chloride of Magnesium. 
2-06 Sulphate of Magnesia. 
1-31 Chloride of Potassium 
1-20 Sulphate of Lime. 
In addition to these constituents, it also contains inappreciable quanti- 
ties of carbonate of lime, magnesia, iron, manganese, phosphate of iime, 
iodides, and bromides, and organic matter, together with ammonia and 
tarbonic acid. — Liebig's Annalen der Chemie, Bd. xxxvii.. s. 3. 



BO OF THE INORGANIC CONSTITUENTS OF PLANTS. 

source from which myriads of marine mollusca and corals are 
supplied with materials for their habitations. 

Whilst the air contains only from 4 to 6 ten-thousandth parts 
of its volume of carbonic acid, sea-water contains 100 times 
more (10,000 volumes of sea-water contain 620 volumes of car- 
bonic acid — Laurent, Bouillon-Lagrange). Ammonia* is also 
found in this water ; so that the same conditions which sustain 
living beings on the land are combined in this medium, in which 
a whole world of other plants and animals exist. 

The roots of plants are constantly engaged in collecting from 
the rain those alkalies which formed part of the sea-water, and 
also those of the water of the springs penetrating the soil. With- 
out alkalies and alkaline bases most plants could not exist, and 
without plants the alkalies would disappear gradually from the 
surface of the earih. 

When it is considered that sea-water contains less ihan one- 
millionth of its own weight of iodine, and that all combinations 
of iodine with the metallic bases of alkalies are highly soluble 
in water, some provision must necessarily be supposed to exist 
in the organization of sea-weed and the diiFerent kinds of Fuci, 
by which they are enabled during their life to extract iodine in 
the form of a soluble salt from sea-water, and to assimilate it in 
such a manner, that it is not again restored to the surrounding 
medium. These plants are collectors of iodine, just as land 
plants are of alkalies ; and they yield us this element in quanti- 
ties such as we could not otherwise obtain from the water without 
the evaporation of whole seas. 

We take it for granted, that the sea plants require metallic 
iodides for their growth, and that their existence is dependent on 
the presence of those substances. With equal justice, then, we 
conclude, that the alkalies and alkaline earths always found in 
the ashes of land plants, are likewise necessary for their deve- 
lopment. 

* When the solid saline residue obtained by the evaporation of sea 
water is heated in a retort to redness, a sublimate of sal-ammoniac i* 
3btained. — Marcet. 



DISINTEGRATION OF ROCKS. SJ 



CHAPTER VIII. 

On the Formation of Arable Land. 

The hardest rocks and stones gra'dually lose their coherence 
when exposed to the influence of certain agencies. Soils cun- 
sist of the debris of rocks which have suffered this change. 

The disintegration of minerals and rocks is effected partly by 
mechanical, and partly by chemical means. It has been re- 
marked in all the mountainous districts of perpetual snow, that 
the most refractory rocks crumble into fragments,* which are 
either rounded by the action of glaciers, or are thoroughly pul- 
verized into dust. The rivers and streams arising out of the 
glaciers are rendered turbid with this mineral debris which they 
deposit on reaching the plains and valleys ; thus fertile soils are 
formed. 

" As often as I have seen beds of mud, sand, and shingle, 
accumulated to the thickness of many thousand feet, I have felt 
inclined to exclaim, that causes such as the present rivers and 
the present beaches could never have ground down such masses. 
But, on the other hand, when listening to the rattling noise of 
these torrents, and calling to mind that whole races of animals 
have passed away from the surface of the globe, during the 
period throughout which, night and day, these stones have gone 
rattling onwards in their course, I have thought to myself. Can 
any mountains, any continent, withstand such waste ?" f 

* " I frequently observed, both in Terra del Fuego and within the 
Andes, that where the rock was covered during the greater part of the 
year with snow, it was shivered in a very extraordinary manner in<o small 
angular fragments. Scoresby has observed the same fact in Spitzhergen ; 
he says : ' The invariably broken state of the rocks appeared to have beer; 
the effects of frost.' " — Darwin' sA^at. Hist, of the Voyage of the Beagle 
p. 388. 

t Darwin, Nat. Hist, of the Voyage of the Beagle, p. 386 
5* 



82 FORMATION OF SOILS. 

In addition to these mechanical causes of waste, we have to 
consider the influence exerted by chemical forces in effecting the 
disintegration of rocks, such as the action of the oxygen and 
carbonic acid of the air, as well as that of water, upon their 
constituent parts. Whilst we apply the term waste to the 
effects produced by mechanical agencies, we shall confine the 
term disintegkation to the effects produced by chemical forces. 
The latter causes may be very gradual in their operation, not 
being limited in regard to time. Hence we cannot refuse to 
acknowledge the existence of their action, even though the effect 
produced may not be sensible during the life of an individual. 

Many years are necessary before the polished surface of an 
exposed fragment of granite loses its polish ; but in process 
of time this is effected, and the large fragment falls to pieces 
under the influence exerted upon its constituents by the chemi- 
cal forces. 

The action of water is so much connected with that of oxygen 
and of carbonic acid, that it is scarcely possible to consider their 
effects apart. 

Many kinds of rocks, such as basalt and clay-slate, contain as 
an ingredient protoxide of iron. This oxide has a great tendency 
to abso]'b oxygen from the air, becoming the higher oxide known 
as peroxide of iron. This property is especially apparent in our 
rich ferruginous soils. The surface of such soils to a certain 
depth is of a red or brownish-red color, an indication that it con- 
tains peroxide of iron ; whilst the black or brownish-black color 
of the subsoil indicates the presence of the protoxide of the same 
metal. It often happens that the subsoil is thrown upon the sur- 
face in the course of subsoil-ploughing, and the consequence on 
such soils is, that their fertility is destroyed for a certain number 
of years. The injury thus received continues until all the sur- 
face-soil again becomes red, that is, until all the protoxide of 
iron is converted into the peroxide. 

It is known that a crystallized salt of iron loses its coherence 
on exposure to air, and crumbles into a powder by the absorption 
of oxygen. In a similar manner the disintegration of most 
minerals is effected, fur their ingredients are susceptible of en- 
tering into union with oxygen. In consequence of the formation 



PROPERTIES OF SILICA. 83 

of new compounds, the coherence of the original body is 
destroyed. If the minerals contain metallic sulphurets, such 
as the pyrites in granite, these are gradually converted into 
sulphates. 

Most kinds of rocks, such as felspar, basalt, clay-slate, por- 
phyry, and the numerous members of the limestone formation, 
consist of compounds of silica, with alumina, lime, potash, soda, 
iron, and protoxide of manganese. 

Before we can properly comprehend the action of water and 
of carbonic acid upon minerals, it is necessary to recollect the 
properties of silica and of its compounds with alkaline bases. 

Quartz forms a very pure variety of silica, and, in this condi- 
tion, it is quite insoluble both in cold and in hot water, is with- 
out taste, and does not exert any action on vegetable colors. 
The principal property of silica in this state is, that it unites with 
alkalies, forming saline compounds, which are termed silicates. 
Window and plate glass consist of mixtures of silicates of the 
alkaline bases, potash, soda, and lime. In such compounds the 
alkali is generally completely neutralized. The property of 
neutralizing metallic oxides and alkalies belongs only to acids, 
and it is owing to this that silica has received the name of silicic 
acid. 

Silica is a very feeble acid, for we have already mentioned 
that, in its crystallized form, it is destitute both of taste and of 
solubility in water ; but 't dissolves when finely pulverized and 
boiled for a long time in alkaline leys. 

We may easily obtain compounds of silica with potash and 
soda, by melting it either with a pure alkali, or with an alkaline 
carbonate. By this treatment white glasses are obtained, differ- 
ing in properties according to their amount of soluble ingre- 
dients. When the glass contains 70 per cent, of silica and 30 
per cent, of potash or soda, it becomes soluble in boiling water. 
Its solution may be spread over a surface of wood or of iron, and 
then dries into a vitreous substance, which has received the 
name of soluble glass. When there is a smaller proportion of 
alkali than the above quantity, or, in other words, when there is 
a larger proportion of silica, the resulting glass diminishes in 
solubility in a greater or less degree. 



64 FORMATION OF SOILS. 

All silicates soluble in water are decomposed by acids. If the 
solution of the silicate contains silica corresponding to more 
than 3^ the weight of the water, the addition of an acid causes 
the formation of a precipitate of a very gelatinous appearance. 
This precipitate, being a compound of silica with water, is 
termed the hydrate of silica. But, if the solution contains less 
silica than the above proportion, no precipitate is formed on the 
addition of an acid, the whole remaining perfectly clear. This 
circumstance proves that silica, in the state in whicl- it is preci- 
pitated by an acid, possesses a certain degree of jolubility in 
pure water. Indeed, by washing with water the |^<?latinous pre- 
cipitate of silica formerly alluded to, its volume diminishes, and 
silica may be detected in solutioa by evaporating the wate» 
which has passed through. 

From these facts we perceive, that silica possscises two distirc > 
chemical characters. In the form in which it id separated frotrt 
a silicate, it possesses quite different properties from those whic*- 
it has when in the state of sand, quartz, or rock crystal. Whep 
sufficient water is present during its separation from a base, U 
effect its solution, the whole remains dissolved ; in certain 
conditions, silica is more soluble in water than gypsum. 

On drying, silica loses completely its solubility in watr» 
The solution of silica in acids acquires, at a certain degree o( 
concentration after cooling, such a gelatinous consistence tha* 
the vessel containing it may be turned upside down withoiM 
spilling a drop of the transparent jelly. By drying it stiji 
further, the water which retained it in the gelatinous condition, 
escapes along with that which had served to hold it in solutioir. 
When the water has been once removed in this way, the silic? 
is no longer soluble in water. But, although it has thus lost it's 
solubility, it does not acquire all the properties of crystallized 
silica, such as sand and quartz, for it still possesses the power o^ 
dissolving in alkalies and alkaline carbonates at the ordinary 
temperature of the air, and this power it retains even when i* 
has been heated to redness. 

There is scarcely any other mineral substance which can be 
compared to silica for the possession of such remarkable proper 
ties as those now described. 



DECOMPOSITION OF FELSPAR. 85 

Most of the insoluble silicates containing alkaline bases are 
decomposed by the action of hot water, particularly when that 
water contains an acid. In the middle of the last century, the 
ignorance of this fact led chemists tg believe that water might 
be converted into an earth. 

When water is distilled in glass vessels, it is found to contain 
always a certain quantity of earthy substances, which may be 
detected by evaporation, even if the water has been subjected to 
many repeated distillations. Lavoisier proved that part of the 
glass was dissolved in this operation by the boiling water ; and 
further, that the diminution in the weight of the glass vessel cor- 
responded exactly to the quantity of earthy residue left by the 
evaporation of the water. When the distillation of water is 
effected in metallic vessels no such residue can be obtained. 

The action of water upon the silicates contained in glass may 
be observed in the opacity which gradually comes over the win- 
dows of hot-beds, these being exposed in a great degree to the 
influence of the air. This action is more marked in the win 
dows of stables, where the carbonic acid formed by the processes 
of respiration of the animals, and by the decay of animal matter, 
accelerates the decomposition. 

Silica being an acid of a very feeble character, the decompo- 
sition of the soluble silicates is effected even by carbonic acid. 

A solution of soluble glass may be converted into a gelatinous 
mass by saturating it with carbonic acid gas. The same decom- 
position must take place in very dilute sotutions, although we 
cannot detect in them any separation of silica, which remains 
dissolved in the water. 

The decomposition of silicates by the combined action of water 
and of acids proceeds with a rapidity proportional to the quantity 
of alkalies contained in them. 

We find numerous examples in the inorganic kingdom of a con- 
tinued and progressing process of decomposition of the silicates 
contained in the various kinds of rocks ; this decomposition is ef- 
fected by the action of carbonic acid, and of water. 

A consideration of the preceding observations shows clearly 
that porcelain clay or kaolin has been formed by the decompos- 
ing action of water on the silicates of potash and soda contained 



8S FORMATION OF SOILS. 



in felspar or felspathic rocks. Felspar* may be viewed as a 
combination of silicate of alumina with silicate of potash ; the 
last of vv'hich being gradually removed by water, leaves behind 
the porcelain clay. 

It has been shown by Forchammer, that felspar may be de- 
composed by water of 150° C. (302° F.), and at a pressure cor- 
responding to this temperature. The water becomes strongly 
alkaline, and is found to contain silica in solution. The hot 
springs in Iceland possess a high temperature, and come from a 
great depth, where they must have been subjected to high pres- 
sure. Forchammer has shown by analysis that the water of 
these springs contains the constituents of soda felspars, and of 
magnesian silicates, minerals of very frequent occurrence in 
trap districts. There cannot be a doubt that a conversion of 
crystalline felspar into clay must be proceeding to a great extent 
at the bottom of these springs. "(■ 

Ordinary water containing carbonic acid acts in precisely 
the same manner as water at a high temperature, and at a high 
pi'essure. 

Polstorf and Wiegmann boiled some white sand with a mixture 
of nitric and muriatic acids, and after completely removing the 

* COMPOSITION OF FELSPATHIC MINERALS. 

Felspar. Albit. Labrador. Anorth. 

Silica - ^ . 56-9. - - 69-8 - - 558 - - 44-5 
Alumina - - - 17-8 - - IS'S - - 26-5 - - 34-5 
Potash - - - 16-3 - . — - . _ . . _ 
Soda - - . — - - 11-4 - . 4-0 - - - 

Magnesia- - - — - - — - - — - - 5"2 
Lime - - . _ - - _ . . u-Q - - 15-7 
Protoxide of iron - — - - — - -TS- - 0'7 

The chemical formula of felspar is AI2, Og 3 Si 0, + KO, Si 0,. 
This formula, when multiplied by three, may be divided into porcelain 
clay, 3 AI2, O3, 4 Si O3, and into soluble silicate of potash, 3 Ko, H 
Si 0,. 

f The dry residue of 2S ounces of the water consisted of— 
Gypsum .... 0'453 
Sulphate of Soda ) 

Magnesia 5 ■ " "'^^^ 
Common Salt - . . 2 264 

Soda 1-767 

&lica 0-506 



ANALYSIS OF PHONOLITE. 87 

Bcid by washing the sand with water, they exposed it thus Duru 
fied to the action of water saturated with carbonic acid gas. 
After the expiration of thirty days, this water was subjected to 
analysis, and was found to contain in solution, silica, carbonate 
of potash, and also lime and magnesia ; thus proving that the 
silicates contained in the sand were unable to withstand the con- 
tinued action of water containing carbonic acid, although the 
same silicates had resisted the short action of the aqua regia. 

Certain of the alkaline silicates found in nature contain in their 
crystalline state water in chemical combination. In this class 
are the zoolites, analcime, mesotype, sodalite, apophyllite, 6ic.; 
the felspars, properly so called, are always anhydrous. 

These silicates differ very much in their behavior to acid 
reagents. When mesotype, or a mineral corresponding to it in com- 
position, is kept in the state of a fine powder in contact with cold 
muriatic acid, it increases in bulk to a thick jelly. The mineral 
being exposed to the action of the acid at the ordinary tempera- 
ture, those constituents which are soluble in the acid are taken 
up by it, whilst the greatest part of the silica remains undissolv- 
ed. Labrador spar (calcareous felspar) behaves similarly when 
treated with acids ; but the minerals adularia and albite (potash 
and soda felspars) are not attacked by acids under similar cir- 
cumstances. 

The difference in properties, with respect to reagents, enables 
us to decompose very complex kinds of rocks into their constitu- 
ent parts. C. Gmelin used a process in the analysis of phonolite, 
or clinkstone rock, by which we may separate and determine 
the amount of the minerals capable of disintegration contained 
in different kinds of rocks or soils submitted to examination. For 
example, phonolite from Abterode in the district of Hegau was 
found to contain* — 

2'097 of a mineral analogous to mesotype, and soluble in acids 
11 '142 of felspar, insoluble in acids 

The constituents of both these are as follows : — 
• Poggendorf's Annalen, Bd. x.,p 357. 



FORMATION OF SOILS. 



The portion Insc!ub:e 

soluble in acids. residue. 

Silica - - - - 38 574 - - G6-291 

Alumina- ... 24-320 - - 16-510 

Potash - ... - 3079 - - 9-249 

Soda .... 12-656 - . 4-960 

Lime .... i-S02 - - A trace. 

Peroxide of iron - - 11-346 - - 2388 

Peroxide of manganese - 2-194 - - 0-896 
Titanic acid - - - 0620 
Water ... - 4-209 
Organic substances - - 0-405 

Jn a similar manner, Frick has analysed clay slate, and Lowe 
the basalt and lava from Mount Etna. 

C 4-615 Magnetic Iron Ore. 
Basalt contains in 100 parts < 39-800 Zeolite.* 
( 55-885 Augite.t 

By treating clay slate from Bendorf with muriatic acid, it was 
decomposed into — 

26-46 parts soluble in muriatic acid. 
73-54 parts insoluble in muriatic acid. 

The composition of these was as follows : — 

Soluble part Insoluble part 

of clay slate. of clay slate. 

Silica 22-39 - - - 7706 

Alumina 19-35 - . - 15-99 

Peroxide of iron 27-61 - - - 1-53 

Magnesia 7-00 ... 057 

Lime - - - - - - - 2-42 - - - 3-94 

Potash without soda .... 2-37 ... 3-94 

Water, carbonic acid, and loss - - 18-86 ... 0-39 
Oxide of copper -.--. ....0-19 

From these analyses we may deduce some highly important 
results. 

It is known that felspar is unable to resist the solvent action 

* Zeolite contains — 

Silica 38-83 

Alumina 28-77 

Lime 1045 

Soda 13-81 

Potash 1-42 

Water , 6-72 

t Augite is a silicate of lime and magnesia 



FORMATION OF CLAYS. 



89 



of water, saturated with carbonic acid, although it is scarcely 
affected by being left in contact with cold muriatic acid for 
twenty-four hours. The analyses given above show that the 
most widely diffused rocks contain a mixture of silicates, which, 
being soluble in cold muriatic acid, must be much more easily 
attacked than felspar by water holding in solution carbonic acid. 

All minerals and rocks containing silicates of alkaline bases 
are incapable of resisting the continued solvent action of carbonic 
acid dissolved in water. The alkalies, with lime and magnesia, 
will either dissolve alone, or the former will enter into solution 
along with silica, while the alumina remains behind, mixed or 
combined with silica. Disintegrated phonolite from Abterode, 
formed by the action of air and moisture on the solid mineral 
(the analysis of which is given abovfe), behaves to acids in a 
manner quite different from the latter. 

The mineral clinkstone contains more than 20 per cent, of 
ingredients soluble in muriatic acid, whilst the same mineral, 
when disintegrated, does not contain more than 5 per cent, of 
soluble constituents.* 

The insoluble portion of disintegrated phonolite is scarcely 
altered in composition : in the soluble portion, iron and mangan- 
ese form the principal constituents : these two oxides exist in the 
soluble portions of the undisintegrated mineral in the proportion 
of 11-346 : 2-194 ; and in the disintegrated mineral, 100 parts 
contain 63-39 of peroxide of iron to 11-3 of peroxide of man- 
ganese, or nearly the same proportion as the former. 

In the process of disintegration, therefore, the alkalies, lime, 
and magnesia, have been dissolved and carried away by water 
along with silica and alumina ; and the residue contains only -^ 
the amount of the alkalies originally present. But as long as 
the mineral contains a trace of an alkali, or of any base soluble 



* The soluble part of disintegrated 


The insoluble portion of disinte- 


clinkstone contains — 




grated clinkstone contains — 




Silica ... - 


13-396 


Silica . . - . 


66-46-3 


Alumina ... 


5-6(30 


Alumina ... 


16S10 


Potash (Soda) 


1-074 


Potash 


9-569 


Lime . - - - 




Soda .... 


4-2S1 


Peroxide of Iron - 


63-396 


Lime .... 


1-5-23 


Peroxide of Manganese - 


11-13-2 


Peroxide of Iron - 


2-9S9 


Titanic Acid 


3-396 


Peroxide of Manganese 


0-1 7-J 



90 FORMATION OF SOILS. 

in carbonic acid, water containing that gas continues to exercise 
an action upon it, and effects a progressive disintegration of its 
constituents. 

Forchammer considers that the yellow clay, which occurs so 
frequently in Denmark, consists of granite, the felspar of which 
has been altered, whilst its mica remains unchanged, and its 
quartz forms the sand of the clay. 

The magnetic and titanic oxides of iron existing in granite are 
still found in the clay as peroxide of iron and titanic acid. 

The blue clays arise from syenite and greenstone ; for in these 
mica is absent (Forchammer). 

The great strata of clay at Halle have had their origin in the 
disintegration of porphyry.* 

The white basis of the clay is easily distinguished by moisten, 
ing it : while the felspar may be recognised by its yellow color 
(Mitscherlich). The silica, dissolved by the potash, or soda, is 
sometimes found deposited in a crystalline form on the crystals 
of felspar ; this is often observed in the trachyte of the Seven 
Mountains near Bonn (Mitscherlich). Most sand-stones contain, 
mixed with them, silicates with alkaline bases. In the sandstone 
of the Holy Mountain near Heidelberg, many unchanged frag- 
ments of felspar are observed, which are partly changed into 
clay and form white points in the sandstone. 

The analysis of the porcelain clays proves that the felspars 
from which they were formed have not reached their utmost 
limit of disintegration, for they still contain potash. The porce- 
lain clays are those which are refractory in the fire, and do not 
melt when exposed to the strongest heat of our furnaces. The 
difficult fusibility of the porcelain clays depends upon their 
small proportion of the alkaline bases, potash, soda, lime, mag- 

* The decomposed felspar, porcelain clay of Mori, near Halle, con« 
gists of — 

Silica 71-42 

Alumina .... 26'07 

Peroxid<^ of iron - - - 1'93 

Lime 0-13 

Potash .... - 0-40 



FORMATION OF CLAYS. 



nesia, and protoxide of iron.* When we compare the other 
kinds of clay with the porcelain clays, we find that the infusible 
clays, or clays poor in potash, are of rare occurrence. The 
clays diffused through the most kinds of rocks, those occurring 
in arable land, and those in the beds of clay interspersed with 
the layers of brown and mineral coal, contract when exposed to 
heat, and become vitrified in a strong fire. Loam also melts in 
a similar manner. When the oxides of iron are not present in the 
clays, their fusibility is in direct proportion to the amount of their 
alkaline ingredients. Clays arising from the disintegration of the 
potash felspars, are free fix)m lime ; those formed from Labrador 
spar (the principal component of basalt and lava), contain lime 
and soda. 

The limestones containing much clay are proportionally the 
richest in alkaline ingredients. The marls and stones used for 
cement belong to this class of minerals. They differ from other 
limestones by possessing the property, after moderate burning, 
of hardening when in contact with water. During the burning 
of marl and of many other natural cements, the constituents of 
the clay and lime act chemically upon each other, giving rise to 
an anhydrous apophyllite, or an analogous compound of silicate 
of potash and silicate of lime, which, being brought in contact 
with water, forces the latter into chemical combination in a man- 
ner similar to burnt gypsum, and crystallizes along with it.f 
When a fragment of chalk is moistened with a solution of silicate 
of potash, the latter forms a new compound on the surface, and 
this becomes hard and stony. The lime of the chalk takes the 
place of potash in the silicate of potash, and a certain quan- 

• COMPOSITIOX OF PORCELAIN CLAYS. 





St. Yvreux. 


Meissen. 


Silica 


- 46-S - 


- 52-8 


Alumina 


- 37-3 - 


- 31-2 


Potash - 


- 2-5 - 


- 2-2. 
Schneeberg. 


Silica 


- 


- 43-6 


Alumina - 


- 


- 37-T 


Peroxide of 


iron 


- 1-5 


Potash and water 


- 12-5 



t Formula of Apophyllite— Ko, 2 Si O3 + 8 Ca 0, Si 3 + 16 aq 



93 FORMATION OF SOILS. 

tity of potash is set at liberty in the form of a carbonate 
(Kuhlmann). 

The preceding considerations prove very clearly that arable 
land has had its origin in the chemical and mechanical actions 
exerted upon rocks and minerals rich in alkalies and alkaline 
earths, by which means their coherence has been gradually 
destroyed. It is scarcely necessary to furnish any further proofs 
that all clays, whether they be pure or mixed with other minerals, 
so as to form soils, suffer progressive and continued changes. 
These changes consist in the giving of a soluble form to the 
alkalies and alkaline bases, by the combined action of water and 
of carbonic acid. This gives rise to the formation of soluble 
silicates, or if these are decomposed by the carbonic acid, to the 
hydrate of silica, which, being in its peculiar soluble condition, 
may be taken up by the roots of plants. 

The influence of air, carbonic acid, and moisture, upon the 
constituents of rocks, is best observed in certain uninhabited dis- 
tricts of South America, where huntsmen and herds are the dis- 
coverers of rich mines of silver. By the action of the weather 
the constituents of the ores of silver are gradually dissolved and 
carried away by winds and by rains ; the nobler metals resist the 
destruction and remain on the surface. It is well known that 
metallic silver veins are found in sharp angular projections from 
the surface of the rock.* 

* Darwin states that the mine at Chanuncillo, from which silver to the 
value of many hundred thousand pounds sterling has been obtained in a 
few years, was discovered by a man who, in throwing a stone after a mule, 
found it heavier than an ordinary stone ; it was a piece of solid 3ilv« r, and 
was a fragment of a projecting vein of that metal. 



INSOLUBILITY OF HUMUS. 93 



CHAPTER IX. 

The Art of Culture. 

The condition? necessary for the life of all vegetables have been 
considered in the preceding part of the work. Carbonic acid, 
ammonia, and water, yield elements for all the organs of plants. 
Certain inorganic substances — salts and metallic oxides — serve 
peculiar functions in their organism, and many of them must bp 
viewed as essential constituents of particular pai'ts. 

The atmosphere and the soil offer the same kind of nourish- 
ment to the leaves and roots. The former contains a compara- 
tively inexhaustible supply of carbonic acid and ammonia ; the 
latter, by means of its humus, generates constantly fresh carbonic 
acid, whilst, during the winter, rain and snow introduce into the 
soil a quantity of ammonia, sufficient for the development of the 
leaves and blossoms. 

The complete, or it may be said, the absolute insolubility in 
cold water of vegetable matter in progress of decay (humus), 
appears on closer consideration to be a most wise arrangement 
of nature. For if humus possessed even a smaller degree of 
solubility than that ascribed to the substance called humic acid, 
it must be dissolved by rain-water. Thus, the yearly irrigation 
of meadows would remove a great part of it from the ground, 
and a heavy and continued rain would impoverish a soil. But 
humus is soluble only when combined with oxygen ; it can be 
taken up by water, therefore, only as carbonic acid. 

When moisture is absent, humus may be preserved for cen- 
turies : but when moistened with water, it converts the surround- 
ing oxygen into carbonic acid. As soon as the action of the air 
ceases, that is, as soon as it is deprived of oxygen, the humus 
suffers no further change. Its decay proceeds only when plants 
grow in a soil containing it ; for they absorb by their roots the 



M THE ART OF CULTURE. 

carbonic acid as it is formed. But the soil receives again from 
living plants the carbonaceous matter it thus loses, so that the 
proportion of humus in it does not decrease. 

The stalactitic caverns in Franconia, and those in the vicinity 
of Baireuth and Streitberg, lie beneath a fertile arable soil ; the 
abundant decaying vegetables or humus in this soil, being acted 
on by moisture and air, constantly evolve carbonic acid, which 
is dissolved by the rain. The rain-water thus impregnated per- 
meates the porous limestone, which forms the walls and roofs of 
the caverns, and dissolves in its passage as much carbonate of 
lime as corresponds to the quantity of carbonic acid contained 
in it. Water and the excess of carbonic acid evaporate from 
this solution when it has reached the interior of the caverns, and 
the limestone is deposited on the walls and roofs in crystalline 
crusts of various forms. There are few spots on the earth where 
so many circumstances favorable to the production of humate of 
lime are combined, if the humus actually existed in the soil in 
the form of humic acid. Decaying vegetable matter, water, and 
lime in solution, are brought together, but the stalactites formed 
contain no humic acid ; they are of a glistening white or yellow- 
ish color, in part transparent, like calcareous spar, and may be 
heated to redness without becoming black. 

The subterranean vaults in the old castles near the Rhine, in 
the " Bergstrass," and in the Wetterau, are constructed of sand- 
stone, granite, or basalt, and present appearances similar to the 
limestone caverns. The roofs of these vaults, or cellars, are 
covered externally to the thickness of several feet with vegetable 
mould, which has been formed by the decay of plants. The rain 
falling upon them, sinks through the eartli, and dissolves the 
mortar by means of the carbonic acid derived from the mould ; 
and this solution evaporating in the interior of the vaults, covers 
them with small thin stalactites, which are quite free from humic 
acid. 

In such a filtering apparatus, built by the hand of Nature, we 
have placed before us the result of experiments which have been 
continued for hundreds or thousands of years. Now, if water 
possessed the power of dissolving a hundred-thousandth part of 
its own weight of humic acid or humate of lime, and if hum'o 



INSOLUBILITY OF HUMUS. 95 

acid were present, we should find tlie inner surface of the roofa 
of these vaults and caverns covered with these substances ; bu' 
we cannot detect the smallest trace of them. We must feel con- 
vinced that humic acid is absent both from the soils of fields and 
of gardens, when we consider that humic acid gives to water a 
dark brown color, whereas well and spring water is quite clear 
and colorless, and leaves after evaporation only a residue of salts 
formed by mineral acids, without humic acid. The water of 
wells and of springs is actually rain-water which, in passing 
through the soil, must exert all its solvent action on the humates. 
If humate of potash existed in soils, all the spring and river water 
collected at a certain depth ought to contain traces of it. But 
even the mineral waters from the springs of Selter and Fachin- 
ger, containing alkaline carbonates, are destitute of a trace of 
humic acid ; although these waters arise in a marshy soil abound- 
ing in vegetable matter. There could scarcely be found more 
clear and convincing proofs of the absence of the humic acid of 
chemists from common vegetable mould. 

The common view adopted respecting the modus operandi of 
humic acid does not afford any explanation of the following phe- 
nomenon : — A very small quantity of humic acid dissolved in 
water gives to it a yellow or brown color. Hence it would be 
supposed that a soil would be more fruitful in proportion as it 
was capable of giving this color to water, that is, of yielding it 
humic acid. But it is very remarkable that cultivated plants do 
not thrive in such a soil, and that all manure must have lost this 
property before it can exercise a favorable influence upon their 
vegetation. Water from barren peat soils and marshy meadows, 
upon which few plants flourish, contains much of this humic 
acid • but all agriculturists and gardeners agree that the most 
suitable and best manure for cultivated plants is that which has 
completely lost the property of giving a color to water. 

The soluble substance, which gives to water a brown color, is 
a product of the putrefaction of all animal and vegetable mat- 
ters ; its formation is an evidence that there is not oxygen sufli 
cient to begin, or at least to complete, the decay. The brown 
solutions containing this substance are decolorized in the air by 
absorbing oxygen, and a black coaly matter precipitates — the sub* 



96 THE ART OF CULTURE. 

stance named " coal of humus." Now if a soil were impreg- 
nated with this matter, the effect on the roots of plants would be 
the same as that of entirely depriving the soil of oxygen ; plants 
would be as little able to grow in such ground as they would if 
hydrated protoxide of iron were mixed with the soil. All plants 
die in soils and water destitute of oxygen ; absence of air acts 
exactly in the same manner as an excess of carbonic acid. 
Stagnant water on a marshy soil excludes air, but a renewal ot 
water has the same effect as a renewal of air, because water 
contains it in solution. When the water is withdrawn from a 
marsh, free access is given to the air, and the marsh is changed 
into a fruitful meadow. 

In a soil to which air has no access, or at most but very little, 
the remains of animals and vegetables do not decay, for they can 
only do so when freely supplied with oxygen ; but they undergo 
putrefaction, for the commencement of which air is present in 
sufficient quantity. Now putrefaction is known to be a most 
powerful deoxidizing process, the influence of which extends to 
all surrounding bodies, even to the roots and the plants themselves. 
All substances from which oxygen can be extracted yield it to 
putrefying bodies ; yellow oxide of iron passes into the state of 
black oxide, sulphate of iron into sulphuret of iron, &c. 

The frequent renewal of air by ploughing, and the prepara- 
tion of the soil, especially its contact with alkaline metallic ox- 
ides, the ashes of brown coal, burnt lime, or limestone, change 
the putrefaction of its organic constituents into a pure process of 
oxidation ; and from the moment at which all the organic matter 
existing in a soil enters into a state of oxidation or decay, its fer- 
tility is increased. The oxygen is no longer employed for the 
conversion of the brown soluble matter into the insoluble coal of 
humus, but serves for the formation of carbonic acid. This 
change takes place very slowly, and in some instances the oxygen 
is completely excluded by it ; and whenever this happens, the 
soil loses its fertility. Thus, in the vicinity of Salzhausen (a 
village in Hesse Darmstadt, famed for its mineral springs), upon 
the meadows of Grunschwalheim, unfruitful spots are seen here 
and there covered with a yellow grass. If a hole be bored from 
wenty to twenty-five feet deep in one of these spots, carbonic 



INSOLUBILITY OF HUMUS. 9V 

acid is emitted from it with such violence that the noise made by 
the escape of the gas may be distinctly heard, at the distance of 
several feet. Here the carbonic acid rising to the surface dis- 
places completely all the air, and consequently all the oxygen, 
from the soil ; and without oxygen neither seeds nor roots can be 
developed ; a plant will not vegetate in pure nitrogen or carbonic 
acid gas. 

Humus supplies young plants with nourishment in the form 
of carbonic acid by the roots, until their leaves are matured 
sufficiently to act as exterior organs of nutrition ; its quantity 
heightens the fertility of a soil by yielding more nourishment in 
this first period of growth, and consequently by increasing the 
number of organs of atmospheric nutrition. Humus acts in 
this respect as a source of carbon to plants ; but vegetable mould 
contains other substances which are equally necessary to plants. 
Vegetable mould contains invariably carbonate of ammonia, 
besides the salts and alkalies left behind by the putrefaction of 
former plants.* Those plants which obtain their first food from 
the substance of their seeds, such as bulbous plants, could com- 
pletely dispense with humus ; its presence is useful only in so far 
as it increases and accelerates their development, but it is not 
necessary — indeed, an excess of it at the commencement of their 
growth is in a certain measure injurious. 

The amount of food capable of being extracted by young 

* Some vegetable mould taken from the interior of a hollow oak, yielded 
xi'o'o' °f residue after incineration ; of this residue 100 parts contained 24 
parts of soluble salts with alkaline bases, 10'5 parts of earthy phosphates, 
10 parts of earthy carbonates, and 32 parts of silica. The aqueous extract 
gave 66 per cent, of soluble salts. (Satjsstjre.) One thousand parts of 
the extract obtained by hot water from vegetable mould formed by the de- 
cay of the Rhododendron Ferrugineum gave 140 parts of ashes, which 
contained, according to Saussure : 

Carbonate of potash - - - 14 
Chloride of potassium - - 23 
Sulphate of potash ... 16 
Earthy phosphates - - - 17 25 
Earthy carbonates - . - 21 "50 

Silica 3-25 

Metallic oxides and loss - • 500 
6 



98 THE ART OF CULTURE. 



plants from the atmosphere, in the form of carbonic acid and 
ammonia, is limited ; they cannot assimilate more than the aif 
contains. Now, if the quantity of their stems, leaves, and 
branches, has been increased by the excess of food yielded by the 
soil at the commencement of their development, they will require 
in a given time for the completion of their growth, and for the 
formation of their blossoms and fruits, more nourishment from 
the air than it can afford, and consequently they will not reach 
maturity. In many cases, the nourishment afforded by the air 
under these circumstances suffices only to complete the forma- 
tion of the leaves, stems, and branches. The same result then 
ensues as when ornamental plants are transplanted from the pots 
in which they have grown to larger ones, in which their roots 
are permitted to increase and multiply. All their nourishment is 
employed for the increase of their roots and leaves; they grow 
luxuriantly, but do not blossom. When, on the contrary, we 
take away part of the branches, and of course their leaves with 
them, from dwarf trees, since we thus prevent the development 
of new branches, an excess of nutriment is artificially procured 
for the trees, and is employed by them in the increase of the 
blossoms and enlargement of the fruit. It is to effect this pur- 
pose that vines are pruned. 

A new and peculiar process of vegetation ensues in all peren. 
nial plants, such as shrubs, fruit and forest trees, after the com- 
plete maturity of their fruit. The leaves of annual plants at 
this period of their growth change in color ; while the leaves of 
trees and shrubs, on the contrary, remain in activity until the 
commencement of the winter. The formation of the layers of 
wood progresses, the wood becomes harder and more solid, but 
after August no more new wood is formed ; all the carbonic acid 
which the plants now absorb is employed for the production of 
nutritive matter for the following year : instead of woody fibre, 
starch is formed, and is diffused through every part of the plant 
by the autumnal sap (seve d'Aout).* According to the observa- 
tions of M. Heyer, the starch thus deposited in the body of the 
tree can be recognised in its known form by the aid of a good 

* Hartig, in Eidmann und Schweigger-Seidels Jourtia], V 217. 1835. 



EXCESS OF NUTRIMENT. 99 

micT'oscope. The barks of several aspens and pine-trees* con- 
lain so much substance, that it can be extracted from them as 
from potatoes by trituration with water. It exists also in the 
roots and other parts of perennial plants. A very early winter, 
or sudden change of temperature, prevents the formation of 
this provision for the following year ; the wood, as in the case of 
the vine-stock, does not ripen, and its growth is in the next year 
very limited. 

From the starch thus accumulated, sugar and gum are pro- 
duced in the succeeding spring, while from these the unnitrogen- 
ized constituents of the leaves and young sprouts are in their turn 
formed. After potatoes have germinated, the quantity of starch 
in them is found to be diminished. The juice of the maple-tree 
loses sugar and ceases to be sweet, when its buds, blossoms, and 
leaves attain their maturity. 

The branch of a willow, which contains a large quantity of 
granules of starch in every part of its woody substance, puts 
forth both roots and leaves in pure distilled or rain-water ; but in 
proportion as it grows, the starch disappears, it being evidently 
exhausted for the formation of the roots and leaves. 

Upon the blossoming of the sugar-cane, likewise, part of the 
sugar disappears; and it has been ascertained, that the sugar 
does not accumulate in the beet-root until after the leaves are 
completely formed. 

These well-authenticated observations remove every doubt as 
to the functions performed by sugar, starch, and gum, in the de- 
velopment of plants ; and it ceases to be enigmatical, why these 
three substances exercise no influence on the growth or process 
of nutrition of a matured plant, when applied to it as food. 

The accumulation of starch in plants during the autumn has 
been compared, although certainly erroneously, to the fattening 
cf hibernating animals before their winter sleep ; but in these 
animals every vital function, except the process of respiration, is 
suspended, and they only require, like a lamp slowly burning, a 
substance rich in carbon and hydrogen to support the process ol 
combustion in the lungs. On their awaking from their torpor in 

• It is well known that bread is made from the bark of pines in Sweden 
during famines. 



100 THE ART OF CULTURE. 

the spring, the fat has disappeared, but has not served as nourish- 
ment. It has not caused the least increase in any part of their 
body, neither has it changed the quality of any of their organs. 
With nutrition, properly so called, the fat in these animals has 
not the least connexion. 

The annual plants form and collect their future nourishment 
in the same way as the perennial ; they store it in their seeds in 
the form of vegetable albumen, starch and gum, which are used 
by the germs for the formation of their leaves and first fibres oi 
the radicle. The proper nutrition of the plants, their increase 
in size, begins after these organs are formed. 

Every germ and every bud of a perennial plant is the en- 
grafted embryo of a new individual, while the nutriment accu- 
mulated in the stem and roots corresponds to the albumen of 
the seeds. 

Nutritive matters are, correctly speaking, those substances 
which, when presented from without, are capable of sustaining 
the life and all the functions of an organism, by furnishing to the 
different parts the materials for the production of their peculiar 
constituents. 

In animals, the blood is the source of the material of the mus- 
cles and nerves ; by one of its component parts, the blood 
supports the process of respiration, by others, the peculiar vital 
functions ; every part of the body is supplied with nourishment 
by the blood, but its own production is a special function, without 
which we could not conceive life to continue. If we destroy the 
activity of the oi-gans which produce it, or if we inject the blood 
of one animal into the veins of another, at all events, if we carry 
this beyond certain limits, death is the consequence. 

The smallest particles of sugar, when left to themselves, 
crystallize, that is, they obey a power strictly chemical. It is 
evident that starch and woody fibre are more highly oi'ganized 
compounds than sugar, for they possess a form which they could 
not have obtained by the mere power of cohesion. We may 
suppose that starch and woody fibre were originally gum and 
sugar, or that both have been formed from sugar ; but certain 
conditions must be necessary for the conversion of sugar into 
gtarch, so that it will n^t be affected when the^e conditions fail. 



CONDITIONS ESSENTIAL TO NUTRITION lOi 

Other substances must be present in a plant, besides the starch,, 
sugar, and gum, if these are to take part in the development oi 
iho germ, leaves, and first fibres of the radicle. There is no 
doubt that a grain of wheat contains within itself the componeni 
parts of the germ and of the fibres of the radicle. These compo- 
nent parts are starch and gluten ; and it is evident that neither 
of them alone, but that both simultaneously assist in the formation 
of the root, for they both suffer changes under the action of air, 
moisture, and a suitable temperature. The starch is converted 
into sugar, and the gluten also assumes a new form, and both 
acquire the capability of being dissolved in water, and of thus 
being conveyed to every part of the plant. Both the starch and 
the gluten are completely consumed in the formation of the first 
part of the roots and leaves ; an excess of either could not be 
used in the formation of leaves, or in any other way. 

The conversion of starch into sugar during the germination ol 
grain is ascribed to a vegetable principle called diastase, which 
is generated during the act of commencing germination. But 
this mode of transformation can also be effected by gluten, al- 
though it requires a longer time. Seeds, which have germinated, 
always contain much more diastase than is necessary for the conver- 
sion of their starch into sugar, for five parts by weight of starch can 
be converted into sugar by one weight of malted barley. This 
excess of diastase can by no means be regarded as accidental, 
for, like the starch, it aids in the formation of the first organs of 
the young plant, and disappears with the sugar. 

Carbonic acid, water, and ammonia, are the food of fully-d^"- 
veloped plants ; starch, sugar, and gum, serve, when accompanied 
by an azotized substance, to sustain the embryo, until its first 
organs of nutrition are unfolded. The nutrition of a foetus and 
development of an egg proceed in a totally different manner from 
that of an animal which is separated from its parent; the exclu- 
sion of air does not endanger the life of the foetus, but would 
certainly cause the death of the independent animal. In the 
same manner, pure water is more advantageous to the growth of 
a young plant than that containing carbonic acid, but after a 
month the rev'erse is the case. (Saussure.) 

The formation of sugar in the maple-trees does not take place 



102 THE ART OF CULTURE. 

in the roots, but in the woody substance of the stem. The 
quantity of sugar in the sap augments until it reaches a certain 
height in the stem of the plajit, above which point it remains 
stationary. 

Just as germinating barley produces a substance which, in 
contact with starch, causes it to lose its insolubility and to become 
sugar, so in the roots of the maple, at the commencement of vege- 
tation, a substance must be formed, which, being dissolved in 
water, permeates the wood of the trunk, and converts into sugar 
the starch, or whatever it may be, which it finds deposited there. 
It is certain, that when a hole is bored into the trunk of a maple- 
tree, just above its roots, filled with sugar, and then closed again, 
the sugar is dissolved by the ascending sap. It is further possi- 
ble that this sugar may be disposed of in the same manner as 
that formed in the trunk ; at all events, it is certain that the 
introduction of it does not prevent the action of the juice upon 
the starch ; and since the quantity of the sugar present is now 
greater than can be exhausted by the leaves and buds, it is ex- 
creted from the surface of the leaves or bark. Certain diseases 
of trees, for example that called honey-dew, evidently depend on 
the want of the due proportion between the quantity of the azo- 
tized and that of the unazotized substances which are applied to 
them as nutriment. 

If now we direct our attention to the particular organs of a 
plant, we find every fibre and every particle of wood surroundec" 
by a juice containing an azotized matter; while the starch, 
granules, and sugar, are enclosed in cells formed of a substance 
containing nitrogen. Indeed everywhere, in all the juices of the 
fruits and blossoms, we find a substance destitute of nitrogen, 
accompanied by one containing that element. 

The wood of the stem cannot be formed, qua wood, in the 
leaves, but another substance must be produced which is capable 
of being transformed into wood. This substance must be in a 
state of solution, and accompanied by a compound containing 
nitrogen ; it is very pi'obable that the wood and the vegetable 
gluten, the starch granules and the cells containing them, are 
formed simultaneously, and in this case a certain fixed propor- 



CONDITIONS ESSENTIAL TO NUTRITION. 103 

tion between them would be a condition necessary for their 
production. 

In the buds and young leaves, we find salts with alkalim bases ; 
we find also the azotized constituents invariably accompanied by 
salts of phosphoric acid : we must, therefore, suppose that these 
substances execute some functions necessary to the support of 
the vital processes of plants. We may suppose that, in the ab- 
sence of certain constituents of the soil, the compounds of plants 
containing nitrogen and sulphur could not be formed, and that 
without the presence of such compounds and of alkaline bases, 
carbonic acid could not be taken up and decomposed. 

According to this view, the assimilation of the substances 
generate' lU the leaves will (cceteris paribus) depend on the 
quantity f nitrogen contained in the food. When a sufficient 
quantity jf nitrogen is not present to aid in the assimilation of 
the subptances destitute of it, these substances will be separated 
as excrements from the bark, roots, leaves, and branches. The 
exudations of mannite, gum, and sugar, in strong and healthy 
plants, cannot be ascribed to any other cause.* 

Analogous phenomena are presented by the process of diges- 
tion in the human organism. In order to restore the loss sus- 
tained by every part of the body in the processes of respiration 
and perspiration, the organs of digestion require to be supplied 
with food, consisting of substances containing nitrogen and of 
others destitute of it, in definite proportion, and also with certain 
mineral substances to effect their transformation into blood. If 
tlie substances dc ?titute of nitrogen preponderate, either they 
vill be expended in the formation of fat, or they will pass un- 
jhanged through the organism. This is particularly observed 

* M. Trapp, in Giessen, possesses a Clerode7idron fragrans growing in 
the house ; it exudes on the surface of its leaves, in September, large 
colorless drops, which form regular crystals of sugar-candy upon drying ; — 
I am not aware whether the juice of this plant contains sugar. Langlois 
has lately observed, during the dry summer in 1842, that the leaves of the 
linden-tree became covered with a thick and sweet liquid, in such quan- 
tity, that for several hours of the day it ran off the leaves like drops of 
rain. Many kilogrammes might have been collected from a moderately- 
iized linden-tree. This sweet juice contained principally grape sugar and 
mannite. {Annates de Chimie et Physique, iii. Serie, torn, vii., p 348.^ 



104 THE ART OF CULTURE. 

in those people who live almost exclusively upon potatoes ; theii 
excrements contain a large quantity of unchanged granules of 
starch. Potatoes, which, when mixed with hay alone, are 
scarcely capable of supporting the strength of a horse, form with 
bread and oats a strong and wholesome fodder. 

It will be evident from the preceding considerations, that the 
products generated by a plant may vary exceedingly according 
to the substances given it as food. A superabundance of carbon 
in the state of carbonic acid conveyed through the roots of plants, 
without being accompanied by nitrogen, cannot be converted 
either into gluten, albumen, or wood ; but either it will be sepa- 
rated in the form of excrements, such as sugar, starch, oil, wax, 
resin, mannite, or gum, or these substances will be deposited in 
greater or less quantity in the wide cells and vessels. 

The quantity of gluten, and of vegetable albumen, will 
augment when plants are supplied with an excess of food con- 
taining nitrogen, if certain other conditions be fulfilled ; and 
ammoniacal salts will remain in the sap, when, for example, as 
in the culture of the beet, we manure the soil with a highly 
nitrogenous substance, or when we suppress the functions of the 
leaves by removing them from the plant. 

We know that the ananas is scarcely eatable in its wild state, 
and that it shoots forth a great quantity of leaves when treated 
with rich animal manure, without the fruit on that account ac- 
quiring a larger amount of sugar; that the quantity of starch in 
potatoes increases when the soil contains much humus, but de- 
creases when the soil is manured with strong animal manure, 
although then the number of cells increases, the potatoes acquir- 
ing in the first case a mealy, in the second a soapy, consistence. 
Beet-roots taken from a barren sandy soil, contain a maximum 
of sugar, and no ammoniacal salts ; and the Teltowa parsnip 
loses its mealy state in a highly manured land, because there 
all the circumstances necessary for the formation of cells are 
united. 

An abnormal production of certain component parts of plants 
presupposes a power and capability of assimilation to which the 
most powerful chemical action cannot be compared. The best 
idea of it may be formed by considering that it surpasses in 



EFFECT OF LIGHT ON CHEMICAL COMBINATIOIS 109 

power the strongest galvanic battery, with which we are not able 
to separate the oxygen from carbonic acid. The affinity of 
chlorine for hydrogen, and its power of decomposing water under 
the influence of light, and of setting at liberty its oxygen, cannot 
be considered as at all equalling the power and energy with 
which a leaf separated from a plant decomposes the carbonic 
acid absorbed by it. 

In living plants and in their seeds, there exists a peculiar 
power ditFerent from all other causes of increase of mass. This 
power, however, only shows itself in action when aided by the 
influence of heat or of light. In spring, when the heat of the sun 
penetrates the earth, the asparagus may put forth shoots of 
many feet in length quite independently of the action of light. 
But the constituents of these shoots were formerly constituents 
of the roots. A conversion of pre-existing compounds into new 
products, and their assumption of new forms, can proceed with- 
out light, although not without heat. But this is not a true in- 
crease of mass, or an increase in the quantity of carbon. I'he 
latter process only takes place under the influence of light. 

The common opinion that only the direct solar rays can eiTect 
the decomposition of carbonic acid in the leaves of plants, and 
that reflected or diffused light does not possess this property, is 
wholly an error, for exactly the same constituents are generated 
in a number of plants, whether the direct rays of the sun fall 
upon them, or whether they grow in the shade. They require 
light, and indeed sun-light, but it is not necessary that the direct 
rays of the sun should reach them. Their functions certainly 
proceed with greater intensity and rapidity in sunshine than in 
the diffused light of day ; but there is nothing more in this than 
Jhe similar action which light exercises on ordinary chemical 
combinations ; it merely accelerates in a greater or less degree 
the action already subsisting. 

Thus chlorine and hydrogen combining form muriatic acid. 
This combination is effected in a few hours in common daylight, 
but it ensues instantly, with a violent explosion, under exposure 
to the direct solar rays, whilst not the slightest change in the 
two gases takes place in perfect darkness. When the oil formed 
from defiant gas is exposed in a vessel with chlorine gas to the 
6* 



106 THE ART OF CULTURE. 

direct solar rays, chloride of carbon is immediately produced ; 
but the same compound can be obtained with equal facility in 
the diffused ligh of day, a longer time only being required. 
When this experiment is performed in the way first mentioned, 
two products only are observed (muriatic acid and perchloride 
of carbon) ; whilst by the latter method a class of intermediate 
bodies are produced, in which the quantity of chlorine constantly 
augments, until at last the whole oil is converted into the same 
two products as in the first case. Here, also, not the slightest 
trace of decomposition takes place in the dark. Nitric acid is 
decomposed in common daylight into oxygen, and peroxide of 
nitrogen ; and chloride of silver becomes black in the diffused 
light of day, as well as in the direct solar rays ; — in short, all 
actions of a similar kind proceed in the same way in diffused 
light as well as in the solar light, the only difference consisting 
in the time in which they are effected. It cannot be otherwise 
in plants, for the mode of their nutriment is the same in all, 
with the exception of certain parasites which obtained their car- 
bon, either not at all, or only partially, from the original source ; 
and their component substances afford proof that their food has 
suffered absolutely the same change, whether they grow in the 
sunshine or in the shade.* 

All the carbonic acid, therefore, which we supply to a plant 
will undergo a transformation, provided its quantity be not 
greater than can be decomposed by the leaves. We know that 
an excess of carbonic acid kills plants, but we know also that 
nitrogen to a certain degree is not essential for the decomposition 
of carbonic acid. All the experiments hitherto instituted prove, 
that fresh leaves placed in water impregnated with carbonic 
acid, and exposed to the influence of solar light, emit oxygen 

* The impossibility of bringing to blossom and seed mosses and other 
cryy)togamous plants, in ordinary daylight, induced Mr. Noller, an excel- 
lent botanist and chemist in Darmstadt, fo form the opinion that the green 
light from the leaves formed a necessary condition of their life. He 
planted numerous kinds of these plants in mouldered wood placed in little 
glass tubes, and covered the whole with a green glass globe. The experi- 
ment established his view in a beautiful manner. All these elegant plants 
developed under these conditions with the greatest lu.xuriance, and put 
forth both blossoms and seedq 



IMPORTANCE OF AGRICULTURE. 107 

gas, whilst the carbonic acid disappears. Now in these experi. 
inents no niti'ogen "s supplied at the same time with the carbonic 
acid ; hence no other conclusion can be drawn from them than 
that a simultaneous introduction of nitrogen is not necessary for 
the decomposition of carbonic acid, — for the exercise, therefore, 
of one of the functions of plants. And yet the presence of a 
substance containing this element appears to be indispensable for 
the assimilation of the products newly formed by the decomposi- 
tion of the carbonic acid, and their consequent adaptation for en- 
tering into the composition of the different organs. 

The carbon abstracted from the carbonic acid acquires in the 
leaves a new form, in which it is soluble and transferable to all 
parts of the plant. In this new form the carbon aids in consti- 
tuting several new products ; these are named sugar when they 
possess a sweet taste, gum or mucilage when tasteless, and ex- 
crementitious matters when expelled by the roots or other parts. 

Hence it is evident that the quantity and quality of the sub- 
stances generated by the vital processes of a plant will vary 
according to the proportion of the different kinds of food with 
which it is supplied. The development of every part of a plant 
in a free and uncultivated state depends on the amount and na- 
ture of the food afforded to it by the spot on which it grows. A 
plant is developed on the most sterile and unfruitful soil as well 
as on the most luxuriant and fertile ; the only difference which 
can be observed being in its height and size, in the number of 
its twigs, branches, leaves, blossoms, and fruit. Whilst the indi- 
vidual organs of a plant increase on a fertile soil, they diminish 
on another where those substances which are necessary for their 
formation are not so bountifully supplied ; and the proportion of 
the constituents containing nitrogen, and those destitute of it, 
varies with the amount of nitrogenous matter in the food of plants. 

The development of the stem, leaves, blossoms, and fruit of 
plants, is dependent on certain conditions, the knowledge of which 
enables us to exercise some influence on certain of their internal 
conscituents as well as on their size. It is the duty of the natural 
philosopher to discover what these conditions are ; for the funda- 
mental principles of agriculture must be based on a knowledge 
of them. There is no profession which can be compared ia 



108 THE ART OF C JLTURE. 

importance with that of agriculture, for to it be longs the produc- 
tion of food for man and for animals ; on it depends the welfare 
and development of the whole human species, the riches of states, 
and all industry, manufacturing and commercial. There is no 
profession in which the application of correct principles is pro- 
ductive of more beneficial effects, or is of greater and more 
decided influence. Hence it appears quite unaccountable, that 
we may vainly search for one leading principle in the writings 
of agriculturists and vegetable physiologists. 

The methods employed in the cultivation of land are different 
in every country, and in every district ; and when we inquire 
the causes of these differences, we receive the answer that they 
depend upon circumstances. {Les circonstances font, les assole- 
ments.) No answer could show ignorance more plainly. 

In addition to the general conditions, such as heat, light, mois- 
ture, and the component parts of the atmosphere, all of which 
are necessary for the growth of all plants, certain substances 
are found to exercise a peculiar influence on their development. 
These substances either are already contained in the soil, or are 
supplied to it in the form of the matters known under the general 
name of manure. But what does the soil contain, and what are 
the components of the substances used as a manure ? Until 
these points are satisfactorily determined, a rational system ot 
agriculture cannot exist. The power and knowledge of the 
physiologistj of the agriculturist and chemist, must be united 
for the complete solution of these questions; and, in order to 
attain this end, a commencement must be made. 

The GENERAL object of agriculture is to produce in the most 
advantageous manner certain qualities, or a maximum size, in 
certain parts or organs of particular plants. Now, this object 
can be attained only by the application of our knowledge of such 
substances as we know to be indispensable to the development of 
these parts or organs, or by supplying the conditions necessary 
lo the production of the qualities desired. 

The rules of a rational system of agriculture should enable 
us, therefore, to give to each plant that which it specially requires 
for the attainment of the object in view. 

The SPECIAL object of agriculture is to obtain an abnormal 



OBJECTS OF AGRICULTURE. 109 

development and production of certain parts of plants, or of 
certain vegetable matters, employed as food for man and animals, 
or for the purposes of industry. 

iiie means employed vary according to the objects which it 
is desired to attain. Thus, the mode of culture employed for 
the purpose of procuring fine pliable straw for Tuscan hats, is 
the very opposite to that which must be adopted in 6rder to pro- 
duce a maximum of corn from the same plant. Peculiar 
methods must be used for the production of nitrogen in the 
seeds, others for giving strength and solidity to the straw, and 
others again must be followed when we wish to give such 
strength and solidity to the straw as will enable it to bear the 
weight of the ears. 

We must proceed in the culture of plants in precisely the 
same manner as we do in the fattening of animals. The flesh 
of the stag and roe, or of wild animals in general, is quite devoid 
of fat, lilie the muscular flesh of the Arab ; or it contains only 
small quantities of it. The production of flesh and fat may be 
artificially increased ; for all domestic animals become fat. We 
give to animals food which increases the activity of certain organs, 
and is itself capable of being transformed into fat. We add to 
the quantity of food, or we lessen the processes of respiration 
and perspiration by preventing motion. 

The increase or diminution of the vital activity of vegetables 
depends only on heat and solar light, which we have not arbitra- 
rily at our disposal : all that we can do is to supply substances 
adapted for assimilation by the power already present in the or- 
gans of the plant. But what then are these substances ? They 
may easily be detected by the examination of a soil always fer- 
tile in the existing cosmical and atmospheric conditions ; for it 
is evident that the knowledge of its state and composition must 
enable us to discover the conditions under which such a soil is 
rendered fertile. It is the duty of the chemist to explain the 
composition of a fertile soil, but the discovery of its proper phy- 
sical state or condition belongs to the agriculturist ; our present 
business lies only with the former. 

Arable land is originally formed by the crumbling of rocks, 
and its properties depend on the nature of their principal compo- 



no THE ART OF CULTURE. 



nent parts. Sand, clay, and lime, are the names given to the 
principal constituents of the different kinds of soil. 

Pure sand and pure limestones, in which there are no other 
inorganic substances except siliceous earth, carbonate or silicate 
of lime, form absolutely barren soils. But argillaceous earths 
form always a part of fertile soils. Now, from whence come 
the argillaceous earths in arable land, what are their constituents, 
and what part do they play in favoring vegetation ? They are 
produced by the disintegration of aluminous minerals, among 
which the common potash and soda felspars, Labrador spar, mica, 
and the zeolites, are those which most commonly undergo this 
change. These minerals are found mixed with other substances 
in granite, gneiss, mica-slate, porphyry, clay-slate, grauwacke 
and the volcanic I'ocks, basalt, clinkstone, and lava. As mem- 
bers of the grauwacke series we have pure quartz, clay-slate, 
and lime ; in the sand-stones, quartz and loam. The transition 
limestone and the dolomites contain an intermixture of clay, 
felspar, porphyry, and clay-slate ; and the mountain limestone is 
remarkable for its quantity of argillaceous earths. Jura lime- 
stone contains 3 — 20, that of the Wurtemburg Alps 45 — 50 per 
cent, of these earths. And in the muschelkalk and in the cal- 
caire grossier they exist in greater or less quantity. 

It is thus obvious that the aluminous minerals are the most 
widely diffused on the surface of the earth, and, as we have 
already mentioned, they are never absent from fertile soils ; 
and, if they should happen to be absent in soils capable of culti- 
vation, this only happens when certain of their constituents are 
supplied by other sources. Argillaceous earth must, therefore, 
contain something which enables it to exercise an influence on 
the life of plants, and to assist in their development. The pro- 
perty on which this depends is that of its invariably containing 
alkalies and alkaline earths, with sulphates and phosphates. 

Alumina exercises only an indirect influence on vegetation, by 
its power of attracting and of retaining water and ammonia ; it 
is itself very rarely found in the ashes of plants,* but silica is 

* Hydrate of alumina, when mixed wit'l: extract of humus, decolorizes 
this substance and renders insoluble the coloring matter. ( Wiegmann 
tmd Polstorf ^ 



FERTILITY OF DIF'^EP.ENT SOILS. Ill 



often present, having in most cases entered the plants by means 
of alkalies. In order to form a distinct conception of the quan- 
titles of alkalies in aluminous minerals, it must be remembered 
that felspar contains 17f per cent, of potash, albite 11 •43 pei 
cent, of soda, and mica 3 — 5 per cent. : — and that zeolites con- 
tain, on an average, 13 — 16 per cent, of alkalies.* The late 
analyses of Ch. Gmelin, Lowe, Fricke, Meyer, and Redten- 
bacher, have also shown, that basalt and clinkstone contain from 
I to 3 per cent, of potash, and from 5 — 7 per cent, of soda ; that 
clay-slate contains from 2'75 — 3-31 per cent, of potash, and 
loam from 1^ — 4 per cent, of potash. 

If, now, we calculate from these data, and from the specific 
weights of the different substances, how much potash must be 
contained in a layer of soil, formed by the disintegration of 26,- 
910 square feet (1 Hessian acre) of one of these rocks to the 
depth of 20 inches, we find that a soil derived from 

Felspar contains - - 1,152,000 lbs. 

Clinkstone '* from 200,000 to 400,000 " 

Basalt " " 47,500 " 75,000 " 

Clay-slate " " 100,000 " 200,000 " 

Loam " " 87,000 " 300,000 " 

The alkalies, potash, and soda, are present in all clays ; at 
least, they have been found in all the argillaceous earths in 
which they have been sought. The fact that they contain potash 
may be proved in the clays of the transition and stratified moun- 
tains, as well as in the recent formations surrounding Berlin, by 
simply digesting them with sulphuric acid, by which process 
alum is formed. (Mitscherlich.) It is well known also to all 
manufacturers of alum, that the leys contain a certain quantity 
of this salt ready formed, the potash of which has its origin from 
the ashes of the stone and brown coal, which k'ontains much 
argillaceous earth. 

A thousandth part of loam mixed with the quartz in new red 
sandstone, or with the lime in the different limestone formations, 
affords as much potash to a soil only twenty inches in depth as 
is sufficient to supply a forest of pines growing upon it for a 

* Recent investigations have shown that potash felspars always contain 
a certain quantity of soda, and that soda felspars always contain potash 



ll'.J THE ART OF CULTURE. 

century, A single cubic foot of felspar is sufficier t to supply an 
oak copse, covering a surface of 26,910 square feet, with the 
potash required for five years. 

Land of the greatest fertility contains argil' aceous earths anc 
other "sintegrated minerals, vi'ith chalk and sand in such a pro- 
portion is to give free access to air and moisture. The land in 
the vicin! v of Vesuvius may be considered as the type of a fer- 
tile soil, aiiu its fertility is greater or less in different parts, ac- 
cording to lis proportion of clay or sand. 

This soil being derived from the disintegration of lava, cannot 
possibly, owing to its origin, contain the smallest trace of vege- 
table matter ; yet every one knows that when lava or volcanic 
ashes have been exposed for a time to the influence of air and 
moisture, all kinds of plants grow in them with the utmost luxu- 
riance. 

This fertility of lava is owing to the alkalies, alkaline eai'ths, 
and silica, contained in it, which by exposure to the weather are 
rendered capable of being absorbed by plants. Thousands of 
years have been necessary to convert stones and rocks into the 
soil of arable land, and thousands of years more will be requisite 
for their perfect reduction, that is, for the complete exhaustion of 
their alkalies. 

We see from the composition of the water in rivers, streamlets, 
and springs, how little alkaJi the rain-water is able to extract 
from a soil, even after a term of years ; this water is generally 
soft, and the common salt, which even the softest invariably con- 
tains, proves that the alkaline salts, which are carried to the sea 
by rivers and streams, are returned again to the land by wind 
and by rain. 

Let us suppose that a soil has been formed by the action of 
the weather on the component parts of granite, grauwacke, moun- 
tain limestone, or porphyry, and that the vegetation upon it has 
remained the same for thousands of years. Now this soil would 
become a magazine of alkalies in a condition favorable for their 
assimilation by the roots of plants. 

The interesting experiments of Struve have proved that water 
impregnated with carbonic acid decomposes rocks containing 
alkalies, and then dissolves a part of the alkaline carbonates. 



DISINTEGRATION OF SOILS. 113 

It is evident that plants also, by producing carbonic acid during 
their decay, and by means of the acids which exude from their 
roots in the living state, contribute no less powerfully to destroy 
the coherence of rocks. Next to the action of air, water, and 
change of temperature, plants themselves are the most powerful 
agents in effecting the disintegration of rocks. 

Air, water, and change of temperature prepare the different 
species of rocks for yielding to plants their alkalies. A soil ex- 
posed for centuries to all the influences which effect the disinte- 
gration of rocks, but from which the alkalies, thus rendered 
soluble, have not been removed, will be able to afford, during 
many years, the means of nourishment to vegetables requiring a 
coiksiderable amount of alkalies for their growth ; but it must 
gradually become exhausted, unless those alkalies which have 
been removed are again replaced ; a period, therefore, will arrive 
when it will be necessary 1o expose it from time to time to a 
further disintegration, in order to obtain a new supply of soluble 
alkalies. For, small as is the quantity of alkali essential to 
plants, it is nevertheless quite indispensable for their perfect de- 
velopment. But when one or more years have elapsed without 
the removal of any alkalies from the soil, a new harvest may be 
expected. 

The first colonists of Virginia found a soil similar to thai 
mentioned above ; harvests of wheat and tobacco were obtained 
for a century from one and the same field, without the aid of 
manure ; but now whole districts are abandoned and converted 
into unfruitful pasture-land, which without manure produces 
neither wheat nor tobacco. From every acre of this land there 
were removed. in the space of one hundred years 12,000 lbs. of 
alkalies in leaves, grain, and straw ; it became unfruitful there- 
fore, because it was deprived of every particle of alkali fit for 
assimilation, and because that which was rendered soluble again 
in the space of one year was not suflicient to satisfy the demands 
of the plants. Almost all the cultivated land in Europe is in 
this condition ; fallow is the term applied to land left at rest for 
further disintegration. It is the greatest possible mistake to sup. 
pose that the temporary diminution of fertility in a soil is owing 



114 THE ART OF CULTURE. 

to the loss of humus ; it is the mere consequence of the exhaus- 
tion of alkalies, and of other essential ingredients. 

Let us consider the condition of the country around Naples, 
which is famed for its fruitful corn-land ; the farms and villages 
are situated from eighteen to twenty-four miles distant from one 
another, and between them there are no roads, and consequently 
no transportation of manure. Now corn has been cultivated on 
this land for thousands of years, without any part of that which 
is annually removed from the soil being artificially restored to it. 
How can any influence be ascribed to humus under such cir- 
cumstances, when it is not even known whether humus was ever 
contained in the soil ? 

The method of culture in that district completely explains the 
permanent fertility. It appears very bad in the eyes of our 
agriculturists, but there it is the best plan that could be adopt- 
ed. A field is ploughed once every three years, and is in the 
intervals allowed to serve as a sparing pasture for cattle. The 
soil experiences no change in the two years during which it lies 
fallow, further than that it is exposed to the influence of the 
weather, by which a fresh portion of its alkalies is again set 
free or rendered soluble. The animals fed on these fields yield 
nothing to them which they did not formerly possess. The weeds 
upon which the cattle live spring from the soil, and the materials 
returned to it in the form of excrements must always be less in 
quantity than those removed as food. The fields, therefore, can 
have gained nothing fi'om the mere feeding of cattle upon them ; 
on the contrary, the soil must have lost some of its constituents. 

Experience has shown in agriculture that wheat should not be 
cultivated after wheat on the same soil, for it, as well as tobacco, 
is of the class of plants which exhaust a soil. But if the humus 
of a soil gives it the power of producing corn, how happens it 
that wheat does not thrive in many parts of Brazil, where the 
soils are particularly rich in this substance, or in our own climate, 
in soils formed of mouldered wood ; that its stalk under these 
circumstances attains no strength, and droops prematurely ? The 
cause is this, that the strength of the stalk is due to silicate of 
potash, and that the corn requires certain phosphates, and tliese 
substances a soil of humus cannot afibrd, since it does not contain 



COMPOSITION OF SOILS. lia 



Vrtcui . ..he plant may, indeed, under such circumstances, become 
a herb, but will not bear fruit. 

Again, how does it happen that wheat does not flourish on a 
sandy soil, and that a calcareous soil is also unsuitable for its 
growth, unless it be mixed with a considerable quantity of clay ? 
It is because these soils do not contain alkalies and certain other 
ingredients in sufficient quantity, the growth of wheat being ar- 
rested by this circumstance, even should all other substances be 
presented in abundance. 

It is not mere accident that we find on soils of gneiss, mica- 
slate, and granite in Bavaria, of clinkstone on the Rhone, of 
basalt in the Vogelsberg, and of clay-slate on the Rhine and in 
the Eifel, the finest forests of oaks, which cannot be produced on 
the sandy or calcareous soils upon which firs and pines thrive. 
It is explained by the fact that trees, the leaves of which are re- 
newed annually, require for their leaves six to ten times more 
alkalies than the fir-tree or pine, and hence they do not attain 
maturity when placed in soils containing very small quantities 
of alkalies.* When we see oaks growing on a sandy or calca- 
reous soil — or the red-beech, the service-tree, and the wild-cherry, 
for example — thriving luxuriantly on limestone, we may be as- 
sured that alkalies are present in the soil, for they are necessary 
to their existence. Can we, then, regard il as remarkable, that 
oak copse should thrive in America, on those spots on which 
forests of pines which have grown and collected alkalies for cen- 
turies, have been burnt, and to which the alkalies are thus at 
once restored ; or that the Spartium scoparium, Erysimum latifo- 
lium, Bliium capitatum, Senecio viscosus, plants remarkable for 
the quantity of alkalies contained in their ashes, should grow 
with the greatest luxuriance on the localities of conflagrations ?f 

* One tho Asand parts of the dry leaves of oaks yielded 55 parts of ashes, 
of which 9^ parts consisted of alkalies soluble in water ; the same qiranti+j 
of pine lea' es gave only 29 parts of ashes, which contain 4"6 parts of solu- 
ble silts. (De Saussure.) 

t After the great fire in London, large quantities of the Erysimum lati- 
foliu7n were observed growing on the spots where a fire had taken place. 
On a similar occasion the Blitnm capitatum. was seen at Copenhagen, the 
Senecio viscosus in Nassau, and the Spartium scoparium in Languedoc. 



116 THE ART OF CULTURE. 

All plants of the grass kind require silicate of potash. Now 
this is conveyed to the .soil, or rendered soluble in it by the irri- 
gation of meadows. The equisetacece, the reeds and species of 
cane containing such large quantities of siliceous earth, or sili- 
cate of potash, thrive luxuriantly in marshes, in argillaceous 
soils rich in potash, and in ditches, streamlets, where the change 
of water renews constantly the supply of dissolved silica. The 
amount of silicate of potash removed from a meadow in the form 
of hay is very considerable. We need only call to mind the 
melted vitreous mass found on a meadow between Manheim and 
Heidelberg after a thunder-storm. This mass was at first sup- 
posed to be a meteor, but was found on examination (by Gmelin) 
to consist of silicate of potash ; a flash of lightning had struck a 
stack of hay, and nothing was founa in its place except the melted 
ashes of the hay. 

Alkalies and alkaline earths are not, however, the only sub- 
stances necessary for the existence of most plants ; but other 
substances besides alkalies are required tosustain the life of plants. 

Phosphoric acid has been found in the ashes of all plants hither- 
to examined, and always in combination with alkalies or alka- 
line earths. By incinerating the seeds of wheat, rye, maize, peas, 
beans, and lentils, ashes are obtained quite free from carbonic 
acid, and consisting entirely of phosphates, with the exception of 
very small quantities of sulphates and of chlorides. 

Plants obtain their phosphoric acid from the soil. Tt is a con- 
stituent of all land capable of cultivation, and even the soil of 
the heath at Liineburg contains it in appreciable quantity. Phos- 
phoric acid has been detected also in all mineral waters in which 
its presence has been tested ; and in those in which it has not 
been found it has not been sought for. The most superficial 
strata of the deposits of sulphuret of lead (galena) contain crys- 
tallized phosphate of lead (green lead ore) ; clay slate, which 
forms extensive strata, is covered in many places with crystals 
of phosphate of alumina ( Wavellite) ; all its fractured surfaces 
are overlaid with this minei'al. 

Apatite (phosphate of lime of similar composition to bone earth) 

After the burnings of forests of pines in North America poplars grew or 
the same soil 



FERTILITY OF SOILS. 117 

is found in every fertile soil. This mineral may be easily reoog- 
nised, in its crystalline form, in many varieties of rocks. It 
occurs in this state in the plutonic, volcanic, and metamorphic 
rocks, although it is usually found only in small quantity. In 
the plutonic and volcanic rocks it is found in granite (as in the 
mines of Johann Georgenstadt, Schneeberg, and in the loose 
gravel near Berlin) ; in syenite it occurs in small crystals, as at 
Meissen, and in larger crystals at Friedrichswern, in South Nor- 
way. It exists also in hypersthene, as at Elfdalen, in Sweden, 
and very often in large quantity, as at Meiches, in the Vogels- 
berge (a district celebrated for its fertility in wheat), and also in 
the hills of Lobau, in Saxony ; Tuhlowitz, in Bohemia, &c. 
It is found in basalt and other volcanic rocks in various localities ; 
for example, at Wickenstein, at Hamberg, and also at Cabo de 
Gata, in Spain, and in the volcanic boulders of the Laacher See. 
Apatite is found also in the metamorphic rocks, and particularly 
in the talc and chloritic schists ; it occurs in large yellow crys- 
tals in the micaceous schists of Snarum, in Norway ; and in the 
calcareous deposits of Pargas, in Finland, and in the Lake Baikal ; 
in the deposits of magnetic iron ore in Arendal, and in other 
places in Sweden and in Norway. It is found also in the 
oceanic rocks, particularly as round fragments and grains in the 
chalk of Cape la Heve, at Havre, and of the Capes Blancnez and 
Grisnez, at Calais, and in the layers of limestone at Amberg, 
&c. (GusTAVus Rose.) 

The water of the imperial spring at Aix la Chapelle contains, 
according to Monheim, 0-142 grains of phosphate of soda in 1 lb.; 
that of the Quirinus Spring contains the same quantity, and the 
water of the Rose spring contains 0-133 of the same salt. The 
water of the fountain of Carlsbad contains 0-0016 grains of phos- 
phate of lime. (Berzelius.) The Ferdinand's spring contains 
0-010 phosphate of soda, according to Wolf. The saline springs 
of Pyrmont contain 0-022 phosphate of potash, 0-075 phosphate 
of lime, and 0-1249 grains phosphate of alumina. (Krueger.) 
When we consider that sea-water contains phosphate of lime in 
such small quantity that its amount cannot be determined in a 
pound of water, and yet from this quantity all the living animab 
in the sea receive the phosphates contained in their bones and flesh, 



118 THE ART OF CULTURE. 

we must admit that the amount of phosphates in the above men- 
tioned mineral waters is very considerable. It may be shown 
by calculation that the water of the fountain at Carlsbad 
must take up many thousand pounds of phosphate of lime in its 
passage through the layers of rocks. 

A few very simple experiments point out the manner in which 
the earthy phosphates, and particularly phosphate of lime, are 
taken up by the roots of plants. 

Phosphate of lime is insoluble in pure water, but it dissolves 
readily in water containing common salt, or a salt of ammonia ; 
and in water containing sulphate of ammonia it dissolves as 
readily as gypsum. Phosphate of lime is also soluble in water 
containing carbonic acid ; in this respect it is analogous to car- 
bonate of lime. 

The soil in which plants grow furnishes their seeds, roots, and 
leaves, with phosphoric acid, and they in turn yield it to 
animals, to be used in the formation of their bones, and of those 
constituents of the brain which contain phosphorus. We may 
form an idea of the quantity of phosphate of magnesia contained 
in grain, when we consider that the concretions in the caecum 
of horses consist of phosphate of magnesia and ammonia, which 
must have been obtained from the hay and oats consumed as 
food. Twenty-nine of these stones were taken after death from 
the rectum of a horse belonging to a miller, in Eberstadt, the 
total weight of which amounted to 3 lbs. ; and Dr. F. Simon has 
lately described a similar concretion found in the horse of a 
carrier, which weighed 1^ lbs. 

Some plants extract other matters from the soil besides 
silica, the alkalies, alkaline earths, sulphuric and phosphoric 
acids, which are essential constituents of the plants ordinarily 
cultivated. These other matters, we must suppose, supply, in 
part at least, the place, and perform the functions, of the sub- 
stances jus>, named. We may thus regard common salt, nitre, 
chloride of" potassium, and other matters, as necessary constitu- 
ents of several plants. 

Clay-slate contains generally small quantities of oxide of 
copper ; and soils formed from micaceous schist contain some 
metallic fluorides. Now, small quantities of these substances 



FERTILITY OF SOILS. 119 

also are absorbed into plants, although we cannot affirm that they 
are necessary to them. 

It appears that in certain cases fluoride of calcium may take 
the place of the phosphate of lime in the bones and teeth ; at 
least it is impossible otherwise to explain its constant presence in 
the bones of antediluvian animals, by which they are distin- 
guished from those of a later period. The bones of human 
skulls found at Pompeii contain as much fluoric acid as those of 
animals of a former world ; for if they be placed in a state of 
powder in glass vessels, and digested with sulphuric acid, the in- 
terior of the vessel will, after twenty-four hours, be found 
powerfully corroded (Liebig) ; whilst the bones and teeth of 
animals of the present day contain only traces of it. (Ber- 

ZELITJS.)* 

In spring and in the first half of the summer, when the 
earth is still moist with water, it is quite certain that a greater 
quantity of alkaline bases and of salts must enter the organism 
of a plant, than in the height of summer, when there is a 
deficiency of water, this being the means of carrying the bases 
to the plant. 

In many districts the crops of corn for the whole year depend 
upon a single shower of rain ; for when water is deficient at a 
certain period of the growth of plants, their future progress is 
retarded. The introduction of water to a soil is, properly speak- 
ing, an introduction of alkalies and of certain salts, which, by 
means of rain-water, become fit to be absorbed by plants. In 
the middle of summer the air is much more charged with the 
vapor of water than at other seasons of the year, and, therefore, 

* The researches of Daubeny, however, tend to show, not only that the 
amount of fluoride of calcium in bones is larger than is commonly sup- 
posed, reaching in some cases to 10 or 12 per cent, of the bone earth, but 
that recent bones contain as much as fossil and ancient bones do. In 
recent bones, however, it cannot be so easily detected, until they have 
been burned, the presence of gelatine seeming to impede the detection of 
fluorine by the usual tests. Dr. G. Wilson has very recently shown that 
fluoride of calcium is soluble in water to an extent quite sufficient to ac- 
count for its very general diffusion. He has found it in sea-water, and in 
all the springs which he has examined. Daubeny suggests that the pre« 
sence of fluoride of calcium in bones may prevent any tendency to crystal 
lization, and thus confer on the bone ndditional toughness. — W. G. 



120 THE ART OF CULTURE. 



the hydrogen which is essential to the nouri.ehment of plants, is 
presented to them in sufficient quantity. 

When the soil is deficient in moisture, we observe a phenome- 
non, which appeared quite inexplicable, before we understood 
the importance of mineral matters, as means of nourishment to 
plants. We see the leaves close to the soil (those which had 
been first developed) lose their vitality, shrink and fall off, 
after becoming yellow, without the apparent action of any inju- 
rious cause. This phenomenon is not perceived, in this form, in 
moist years, nor is it observed with evergreens, and only rarely 
with those plants which throw out long deep roots ; it is observed 
only in harvest and in winter with perennial plants. 

The cause of this phenomenon is now quite apparent. The 
matured leaves absorb continually from the air carbonic acid 
and ammonia, which are converted into the constituents of new 
leaves, buds, and twigs ; but this conversion cannot be effected 
without the co-operation of alkalies and of other inorganic sub- 
stances. When the soil is moist these are constantly conveyed 
to the plants, which retain their green color in consequence. 
But in dry weather, the deficiency of water prevents them being 
absorbed by the plant ; and in consequence of this, they are 
taken from the plant itself. The mineral ingredients in the juice 
of the fully formed leaves are abstracted from them, and are 
employed in the formation of the young sprout ; and when the 
seeds become developed the vitality of the old leaf is completely 
destroyed. These withered leaves contain mere traces of soluble 
salts, while the buds and sprouts are remarkably rich in these 
ingredients. 

The reverse of this phenomenon is seen in the case of many 
kitchen plants, when they are supplied with rich manure con- 
taining an excess of mineral ingredients ; salts are separated 
from the surface of their leaves, and cover them with a thin 
white crust. In consequence of these exudations the plant be- 
comes sickly, the organic activity of the leaves diminishes, the 
growth of the plant is destroyed, and if this condition lasts, the 
plant finally dies. These observations are best made on plants 
with leaves of large dimensions, through which large quantities 
of water are evaporated. 



FERTILITY OF SOILS. 12l 



This disease generally attacks turnips, gourds, and peas, 
when the soil is drenched with sudden and violent rain, after 
continued dry weather, at the time when the plants are near, but 
have not attained maturity ; it is also necessary for its occur- 
rence, that dry weather should again happen after the rain. 

By the rapid evaporation of the water absorbed by the roots, 
a laiger quantity of salts enters the plants than they are able to 
use. The salts effloresce on the surface of the leaves, and 
when ihey are juicy, act as if the plants had been treated with 
solutions of salts, in greater quantity than their organism could 
bear. Of two plants of the same kind the one nearest maturity 
is most liable to this disease ; if the other plant has either been 
planted at a later period, or if its development has been restrain- 
ed, the causes, which exercised injurious effects upon the first 
plant, accelerate the development of the latter. The germ 
springing out of the earth, the leaf on coming out of the bud, the 
young stem, and the green sprouts, contain a much larger quan- 
tity of salts with alkaline bases and give ashes on incineration 
much richer in alkaline ingredients, than parts of the matured- 
plant. The leaves, being the part in which the absorption and 
decomposition of carbonic acid is effected, are much richer in 
mineral ingredients than other parts of the plant. 

The simple fact that a plant is restrained in growth by the 
want of rain to convey to it alkalies, proves completely that these 
alkalies play a most important part in vegetation. 

Although it was found by Saussure that wheat before blossom- 
ing yielded Vo^j i" blossom -yf^, and after the ripening of the 
seeds only half this quantity of ashes ; it cannot hence be con- 
cluded that the ingredients of the soil present in the young and 
growing plants, were again returned to the soil. Equal quanti- 
ties of young plants yield twice the amount of ashes that matured 
plants do ; but this evidently arises from the circumstance, that 
new quantities of organic constituents are added to the carbon, 
hydrogen, and nitrogen, previously existing in the young plant. 
The amount of ashes remains the same in both plants, ahhouglj 
their relative proportions have become different. 

We may feel assured that the alkalies contained in the vine, 
in the potatoe, and beet, and found in the juices, united with tar. 
7 



122 THE ART OF CULTURE. 

taric, citric, oxalic, and malic acids, are not merely present for 
the purpose of being used in druggists' shops, or in our house- 
hold, as ac.ii or as neutral salts. These organic acids must be 
necessary for the formation of certain constituents in the plants. 

We have already come to the conclusion, that the carbon of 
all plants is derived from carbonic acid ; tartaric, oxalic, citric 
acid, &c., must, therefore, obtain their carbon from the same 
source. But, can we conceive that the carbon forms a direct 
and immediate combination with hydrogen for the production of 
substances so various as sugar, starch, woody fibre, resin, wax, 
and oil of turpentine ? Is it not much more probable that the 
conversion of the carbon of carbonic acid into the constituent of 
a plant proceeds in a gradual manner ; that by the union of the 
constituents of water with carbonic acid, a substance is formed, 
becoming gradually poorer in oxygen ; and that the carbon as- 
sumes the form of oxalic, tartaric, or other organic acids, before 
it is converted into sugar, starch, or woody fibre ? 

According to this view, a ready and simple explanation is fur- 
nished of the necessity of alkalic bases to vegetable life ; for 
they are present for the purpose of effecting the conversion of 
carbonic acid into a living part of a plant. The smallest parti- 
cles of sugar, or of organic acids, when separated from plants, 
follow their own peculiar attractions ; they form crystals, or they 
follow the power which induces the cohesion of their atoms, but 
still their carbon is capable of being converted into a constituent 
of a living organ ; and, although sugar and tartaric acid have 
been formed by vital agencies, they do not in themselves possess 
any vital functions. 

From the preceding part of this chapter it will be seen thai 
fallow is that period of culture when the land is exposed to pro- 
gressive disintegration by the action of the weather, for the pur- 
pose of liberating a certain quantity of alkalies and silica to be 
absorbed by future plants. 

The careful and frequent working of fallow land will accele- 
rate and increase its disintegration ; for the purposes of culture it 
is quite the same whether the land be covered with weeds, or 
with a plant which does not extract the potash of the soil. 



SCIENCE AND PRACTICE. IM 



CHAPTER X. 

On Fallow. 

Agriculture is both an art and a science. Its scientific basis 
embraces a knowledge of all the conditions of vegetable life, of 
the origin of the elements of plants, and of the sources whence 
they derive their nourishment. 

From this knowledge fixed rules are formed for the practice 
of the art, that is, for the necessity or advantage of all the 
mechanical operations of the farm, by which the land is prepared 
for the growth of plants, and by which those causes are removed, 
which might exercise an injurious influence upon them. 

Experience acquired in the practice of this art can never stand 
in contradiction to its scientific principles ; because the latter 
have been deduced from all the observations of experience, and 
are actually an intellectual expression of it. Neither can The- 
ory ever stand in antagonism to Practice, for it is merely the 
tracing back of a class of phenomena to their ultimate causes. 

A field upon which we cultivate the same plants successively 
for a number of years, may become unfertile for these plants in 
'.hree years ; whilst another field may last seven, another twenty, 
and another one hundred years, without losing its fertility. One 
field bears wheat but not beans ; another bears turnips but not 
tobacco ; and a third yields rich crops of turnips, but does not 
bear clover. 

What is the reason that a field loses gradually its fertility for 
the same plant ? What is the reason that a certain kind of plant 
flourishes on it, and that another fails ? 

These questions are proposed by the Science of Agri- 
culture. 

What means are necessary to enable a field to sustain its fer» 



124 ON FALLOW. 



tility for the same plant, and to make it fit for the cultivation of 
one, two, or for all plants ? 

The latter, questions are proposed by the art of Agri- 
CULTUR.! ; but they are not susceptible of solution by means of 
the art. 

When a farmer institutes experiments for the purpose of mak- 
ing a field fertile for plants which it would not formerly bear, 
the prospect of success must be small, unless he is guided by 
scientific principles. Thousands of farmers try analogous expe- 
riments in various ways, and the results of these constitute a 
mass of experience, out of which a method of culture is finally 
formed ; and this method suffices for a certain district. But the 
same method fails with a neighboring district, or it may prove 
actually injurious. 

What an immense amount of capital and power is lost in such 
experiments as these ! What a very different and much more 
certain path does Science follow ! It does not put us in danger 
of failure, and it gives us the best security of success. 

If the causes of failure or the causes of sterility of a soil for 
one, two, or three plants be ascertained, the means of obviating 
the sterility follow as a matter of course. 

The methods of cultivating soils vary with their geological 
characters. In basalt, grauwacke, porphyry, sandstone, lime- 
stone, &c., let us suppose that there are present, in different 
proportions, certain chemical compounds essential to the growth 
of plants, and which must therefore exist in fertile soils; then 
we are able to explain in a very simple manner the difference 
in the methods of culture ; for it is obvious that the soils formed 
by the disintegration of the above rocks must vary in the pro- 
portion of their essential constituents, just as the rocks themselves 
vary. 

Wheat, clover, and turnips, require certain constituents from 
the soil ; and hence they cannot flourish in a soil from Avhich 
these are absent. Science enables us to recognise these neces- 
sary constituents, by the analysis of the ashes of the plants ; and 
if we discover the absence of these ingredients from the soil, the 
cause of its sterility is obvious. 



WEATHERING OF ORES. 120 

The means of obviating this sterility follows from a knowledge 
of its cause. 

Empiricism ascribes all results to the art, that is, to the me- 
chanical operations employed in cultivation, without inquiring 
the causes upon which their use depends. But a knowledge of 
these causes is of the highest importance ; for such knowledge 
would prevent the lavish expenditure of capital and of power, 
and would enable us to use them in the most advantageous man- 
ner. Is it conceivable that the entrance of the ploughshare or 
of the harrow into the earth — that the contact of iron with the 
soil — can act as a charm to impart fertility ? No one can enter- 
tain such an opinion ; and yet the causes of their action have noi 
yet been inquired into, and much less have they been explained. 
It is quite certain that it is the great mechanical division, the 
change and increase of surface, obtained by the careful plough- 
ing and breaking up of the soil, which exercises so very favora- 
ble an influence on its fertility ; but these mechanical operations 
are only the means to attain that end. 

Among the effects produced by time, particularly in the case 
of fallow, or that period during which a field remains at rest, 
science recognises certain chemical actions, which proceed unin- 
terruptedly by means of the influence exercised by the constitu- 
ents of the atmosphere upon the surface of the solid crust of the 
earth. By the action of the carbonic acid and oxygen in the air, 
aided by moisture and by rain-water, the power of dissolving in 
water is given to certain constituents of rocks, or of their debris, 
from which arable land is formed ; these ingredients, in con- 
sequence of their solubility, become separated from the insoluble 
constituents. 

These chemical actions serve to explain the effects produced 
by the hand of time, which destroys human structures, and con- 
verts gradually the hardest rocks into dust. It is by their influ- 
ence that certain ingredients of arable land become fit for assimi- 
lation by plants; and the object of the mechanical operations of 
the farm is to obtain this result. Their action consists in acce- 
lerating the weathering or disintegration of the soil, and thus 
ofTers to a new generation of plants their necessary mineral con- 
stituents, in a form fit for reception. The celerity of the disin 



126 ON FALLOW. 



tegration of a solid body must be in proportion to its surface , 
for the more points which we expose to the action of the destrue 
tive agencies, the more rapidly will their effects be produced. 

When a chemist subjects a mineral to analysis, in order to 
break up the compound, that is, to give solubility to its constitu- 
ents, he is obliged to perform the very tedious and difficult task 
of reducing it to an impalpable powder. He separates the fine 
dust from the grosser particles by means of a fine sieve, or by 
elutrialion, and exerts his utmost patience to obtain a fine pow- 
der ; because he is aware that the solution of the mineral will 
be incomplete, and that all his operations will prove ineffectual, 
if he be at all careless in this preliminary operation. 

The influence of an increased surface upon the weathering ol 
a stone, or, in other words, on the changes which it suffers by the 
action of the constituents of the atmosphere, and by water, is 
very well pointed out in the interesting description given by Dar- 
win of the gold mines at Yaquil, in Chili. The gold ores, after 
being reduced to a very fine powder in mills, are subjected to a 
process by which the particles of metal are separated from the 
lighter parts of the ore. The particles of stone are carried away 
by a stream of water ; while those of gold fall to the bottom. 
The former are conducted into a tank, where they are permitted 
to deposit. As the tank fills gradually, the fine mud is removed 
from it, and is left in heaps to itself, that is, it is exposed to the 
action of the air and of moisture. From the nature of the elutria- 
tion to which it was subjected, the finely-divided ore can no longer 
contain any salts, or soluble ingredients. Whilst it lay at the 
bottom of the tank covered with water, and therefore excluded 
from air, it suffered no change ; but when exposed to air, a pow- 
erful chemical action ensues in the heaps, and this action is 
recognised by the abundant efflorescence of salts, which cov( i 
their surface, from the effects of disintegration. After the finely 
divided ore has been exposed to the action of the weather for two 
or three years, during which time it hardens, it is again elutri- 
ated, and the processes of exposure and elutriation are repeated 
six or seven times, new quantities of gold being obtained each 
time, although in smaller proportions ; this gold is liberated by 
the chemical process of weathering or of disintegration. 



ACTION OF IJME. 121 



The same chemical actions as those now described proceed in 
our arable land, and it is to accelerate and increase these that we 
employ the mechanical operations of culture. We renew the 
surface of the soil, and endeavor to make every particle of it 
accessible to the action of carbonic acid and of oxygen. Thus 
we procure a new provision of soluble mineral substances, which 
are indispensable for the nourishment and luxuriance of a new 
generation of plants. 

All cultivated plants require alkalies and alkaline earths, 
although each of them may use different proportions of the one 
or of the other ; the cereals do not flourish in a soil deficient in 
silica in a soluble state. 

Silicates, as they occur in nature, differ very materially in 
their tendency to suffer disintegration, and in the resistance 
which they offer to the action of atmospheric agents. The 
granite of Corsica and the felspar of Carlsbad crumble into dust 
in a space of time during which the polished granite of the Berg- 
strasse does not even lose its lustre. 

There are certain kinds of soil so rich in silicates prone to 
disintegration, that every year, or every two years, a quantity of 
silicate of potash is rendered fit for assimilation sufficient for the 
formation of the leaves and stems of a whole crop of wheat. In 
Hungary there are large districts of land, on which, since the 
memory of man, corn and tobacco have been cultivated in alter- 
nate years, without the restoration of the mineral ingredients 
carried away in the corn and in the straw. There are other 
fields, on the contrary, which do not yield sufficient silicate of 
potash until after two, threfl, or more years. 

Fallow, in its most extended sense, means that period of cul- 
ture during which a soil is exposed to the action of the weather, 
for the purpose of enriching it in certain soluble ingredients. lu 
a more confined sense, the time of fallow may be limited to the 
interval inthe cultivation of cereal plants ; for a magazine of 
soluble silicates and of alkalies is an essential condition to the 
existence of such plants. The cultivation of potatoes or of tur- 
nips during the interval will not impair the fertility of the field 
for the cereals which are to succeed (supposing the supply of 



128 ON FALLOW. 



alkalies to be sufficient for both), because the former plants do not 
require any of the silica necessary for the latter. 

It follows from the preceding observations, that the mechanical 
operations in the field are the simplest and most economical means 
of rendering accessible to plants the nutritious matters in the soil. 

But, it may be asked, are there no other means besides the 
mere mechanical operations, of liberating the ingredients of a 
soil, and of fitting them for reception by the organism of plants ? 
There are such means, and one of the most simple and efficacious 
of them is the practice employed in England for the last century, 
of manuring soils with burnt lime. 

In order to form a proper conception of the action of lime on 
soils, we must remember the processes employed by chemists 
to effect the speedy decomposition of a mineral, and to render 
soluble its ingredients. In order to dissolve finely-pulverized 
felspar in an acid, it would be necessary to expose it to continued 
digestion for weeks, or even for months. But when the felspar 
is mixed with lime, and is exposed to a moderately strong heat, 
the lime enters into chemical combination with the constituents 
of the felspar. A part of the alkali (potash) imprisoned in the 
felspar is now set at liberty, and a simple treatment of the felspar 
with acid, in the cold, now suffices to dissolve the lime and the 
other constituents of the mineral. The silica is dissolved by the 
acid to such an extent, that the whole assumes the consistence oi 
a transparent jelly. 

Most of the silicates of alumina and alkalies, when mixed 
with slacked lime and kept in continued contact in a moist state, 
behave in a similar manner to felspar when heated with lime. 
When a mixture of common clay, or of pipe-clay, and water, is 
added to milk of lime, the whole becomes immediately thicker on 
agitation. When they are left in contact for several months, it 
is found that the mixture gelatinizes on the addition of an acid — 
a property which the mixture of clay and w^ater did not possess, 
or only to a very small degree, before the contact with lime. 
The clay is broken up by the union of certain of its constituents 
with lime ; and, what is still more remarkable, most of the alka- 
lies contained in it are set at liberty. These beautiful observa- 
tions were first made by Fuchs of Munich j and they have not 



BURNING OF LAND. ♦2i 



only led to conclusions on the nature and properties of hydraulic 
limestones, but, what is far more important, they have explained 
the action of slacked lime upon soils, and they have thus furnish, 
ed an invaluable means of liberating from the soil the alkalies 
which are indispensable to the existence of plants. 

In October, the fields in Yorkshire and Lancashire have the 
appearance of being covered with snow. The soil for miles is 
seen covered either with lime previously slacked, or with lime 
that has slacked itself by exposure to air. During the moist 
months of winter, it exercises its beneficial influence on the stiff 
clayey soils. 

According to the old theory of humus, we ought to suppose 
that burnt lime would exercise a very injui'ious influence on soils, 
by destroying the organic matter contained in them, and by thus 
rendering them unfit to supply a new vegetation with humus. 
But, on the contrary, it is found that lime heightens the fertility 
of a sol. The cereals require the alkalies and silicates liberated 
by the lime and rendered fit for assimilation by plants. If there 
be present decaying matter yielding to the plants carbonic acid, 
their development may be favored by this means ; but this is 
not necessary. For if we furnish to the soil ammonia, and to 
the cereals the phosphates essential to their growth, in the event 
of their being deficient, we furnish all the conditions necessary 
for a rich crop, as the atmosphere forms an inexhaustible maga- 
zine of carbonic acid. 

In districts where fuel is cheap, an equally favorable influence 
is exerted on clayey soils by the system of burning. 

It is not very long since that chemists observed the remarka- 
ble changes which take place in the properties of clay when it is 
burned : these were first studied in the analysis of several sili- 
cates of alumina. Many of them, which are not at all attacked 
by acids in their natural state, acquire complete solubility when 
they, are previously melted by heat. To this class of silicates 
belong pipe and potter's clay, loam, and the different varieties of 
clay occurring in soils. In the natural state of clay, it may be 
digested with concentrated sulphuric acid for hours, without dis- 
solving in any appreciable quantity ; but v/hen the clay i? slightly 
burnt (as is done, for example, in several alum works) it dissolves 
7* 



130 ON FALLOW. 



in acids with great ease, while the silica is separated in its gela- 
tinous and soluble form. Common potter's clay forms generally 
very sterile soils, although it contains within it all the conditions 
for the luxuriant growth of plants ; but the mere presence of 
these conditions does not suffice to render them useful to vegeta- 
tion. The soil must be accessible to air, oxygen, and carbonic 
acid, for these are the principal conditions to favor the develop- 
ment of the roots. Its constituents must be contained in a state 
fit to be taken up by plants. Plastic clay is deficient in all these 
properties, but they are communicated to it by a gentle calcina- 
tion.* 

The great difference between burnt and unburnt clay may be 
observed in places where burnt bricks are used for building. 
In Flanders, where almost all the houses are constructed with 
burnt bricks, the surface of the walls, after exposure for a few 
days to the action of the weather, becomes covered with an efflo- 
rescence of salts. When these salts are washed away by the 
rain, a new efflorescence again appears ; and in some cases, as 
the gateway of the fortress at Lille, this may be observed, even 
though the walls have stood for centuries. The efflorescence 
consists of carbonates and of sulphates with alkaline bases — salts 
that are known to play a most important part in the economy of 
vegetation. Lime exercises a striking effect upon these saline 
efflorescences, for it may be observed, that they first appear in 
those parts where the mortar and bricks come in contact. 

It is obvious that mixtures of clay and lime contain all the con- 
ditions necessary for the decomposition of the silicate of alumina, 
and for rendering soluble the alkaline silicates. Lime dissolved 
in water by means of carbonic acid acts upon clay in the same 
way that milk of lime does. This fact explains the flivorable 
influence of marl upon most soils, marl being a clay rich in lime. 
Indeed there are certain marly soils surpassing in fertility, for all 
plants, soils of any other kind. Burnt marl must be in a -very 

* The author saw an example of this in the garden of Mr. Baker, at 
Hardvvick Court, near Gloucester. The soil consisted of a stiff clay, and, 
from a state of complete sterility, had b^en made remarkably fertile, by 
simple burning. The operation, in this case, was carried on to a depth of 
three feet, — certainly not an economical, although a completely successful 
experiment. 



PHYSICAL STATE OF SOILS. 13i 

superior state for manure ; and this remark applies to all sub. 
stances of a similar composition, — to the hydraulic limestones, 
for example. By these the plants are furnished, not only with 
alkalies, but also with silica, in a state fit for reception. Many 
of the hydraulic limestones, or the natural cements, as they are 
called, after being mixed in their burnt state with water, yield to 
it, in a few hours, so much caustic alkali, that the water may be 
employed as a weak ley for the purposes of washing. 

The ashes of brown coal and of mineral coal are used in many 
districts as excellent means of improving certain soils. Those 
ashes are to be preferred that gelatinize on the addition of an acid, 
or that become stony and hard after some time, like hydraulic 
cement, when mixed with lime and water. 

The mechanical operations of the farm, fallow, the applications 
of lime, and the burning of clay, unite in elucidating the same 
scientific principle. They are the means of accelerating the 
disintegration of the alkaline silicates of alumina, and of sup- 
plying to plants their necessary constituents at the commence- 
ment of a new vegetation. 

It must be distinctly understood, that the previous remarks 
apply only to those fields which are in a favorable mechanical 
state for the development of plants ; for this, in conjunction with 
the other necessary conditions, has the greatest influence on fer- 
tility. A stiff, heavy clayey soil offers too much resistance to 
the spreading out and increase of the roots of a quick-growing 
summer plant. It is obvious that such a soil will be rendered 
more accessible to the roots, as well as to air and moisture, by a 
simple mixture with quarz or with sand, and this may often prove 
more effectual in improving it than the most diligent ploughing. 
When we supply to a soil easily penetrable by the roots of plants, 
as well as by air and moisture, in the form of ashes, the consti- 
tuents that we rei loved in the crops, the soil will retain all its 
original favorable physical state. In like manner, we can restore 
the original chemical composition to stiff, heavy clay soils ; 
but it is better for such soils to restore the necessary ingredients 

IN THE FORM Of STABLE VARD MANURE, than to do SO, as in the 
former case, by means of ashes. By the improvement of the 
physical condition of the soil, its fertility is increased. In this 
respect excrements are of very various values, although th"v mnv 



132 ON FALLOW. 



contain the same chemical constituents ; thus sheep's dung is 
close and heavy, while the dung of cows and of horses, especially 
when mixed with straw, is light and pcrous. 

In hot summers, accompanied by light and partial showers of 
rain, porous soils of no great fertility yield often better crops 
than richer stiff soils. The rain falling on the porous soil is im- 
mediately absorbed and reaches the roots, whilst that falling on 
the heavy soils is evaporated before it is enabled to penetrate 
them. 

A soil destitute of cohesion, like quick-sand, is not fitted for 
the cultivation of plants in general. Finally, there are certain 
kinds of soils which ought, from their chemical composition, to 
be very fertile, but which, on the contrary, are sterile for many 
kinds of plants : such soils are those that ponsist of clay mixed 
with a large quantity of very fine sand. Such a soil converts 
itself into a kind of thick mud after a heavy fall of rain, and thus 
prevents all access of air, and it dries without much contraction. 

If we were to apply, in all their extent, to porous, sandy, or 
calcareous soils, or to a soil of the nature mentioned above, the 
principles upon which depend the improvement of land by fallow, 
we could not hope to obtain favorable results. A soil of great 
porosity, through which water penetrates with great ease, and 
which does not yield sufficient hold to the roots of plants, and also 
a stiff soil, with its particles too finely divided, and of small fer- 
tility on account of its physical properties, cannot be benefited by 
the mechanical operations of the field ; for these are intended to 
effect a still further reduction of the particles. 

The physical conditions essential to the fertility of a soil are 
usually neglected in the calculations of the chemist, and thus 
render a mere chemical analysis of very subordinate value ; for 
the existence of all the mineral means of -lourishment in a soil 
does not necessarily indicate its value. But when the chemical 
is combined with the mechanical analysis* (for the latter of which 
Mr. Rham has described an equally simple and convenient instru- 
ment), then we are furnished with data upon which to form 
accurate conclusions. 

• The estimation of the unequal quantities of mixed ingredients, sucb 
as of the coarse and fin? pand, and of the clay and vegetable inatter? 



MINERAL SUBSTANCES IN ANIMAL BODIES. 13* 



CHAPTER XI. 

On the Rotation of Crops. 

It has been shown, by accurate examinations of animal bodies, 
that the blood, bones, hair, &c., as well as all the organs, contain 
a certain quantity of mineral substances, without the presence of 
which in the food, these tissues could not be formed. 

Blood contains potash and soda in combination with phosphoric 
acid ; the bile is rich in alkalies and sulphur ; the substance of 
the muscles contains a certain amount of sulphur ; the blood 
globules contain iron ; the principal ingredient of bones is phos- 
phate of lime ; nervous and cerebral substance contains phos- 
phoric acid and alkaline phosphates ; and the gastric juice 
contains free muriatic acid. 

We know that the free muriatic acid of the gastric juice and 
part of the soda of the bile is obtained from common salt ; 
and we are enabled, by the mere exclusion of this material 
from food, to put an end to the digestive process and life of an 
animal. 

When a young pigeon is fed upon grains of wheat in which 
phosphate of lime, the principal constituent of the bones, is defi- 
cient, and when it is prevented receiving this substance from 
other sources, its bones become thin and friable, and death ensues 
if the supply of this mineral substance is still prevented. 
(Choiset, Report to the Academy of Paris, June, 1842.) In 
like manner, if we exclude carbonate of lime from the food of 
fowls, they lay eggs without the hard exterior shell. 

When a cow is fed upon an excess of roots, such as potatoes 
and turnips, the same thing must happen to it, as in the case of 
the pigeon cited above ; for these roots contain phosphate of 
magnesia, and only traces of lime. Now, if we remove daily 
from the same cow a certain amount of phosphate of lime in its 



134 ROTATION OF CROPS. 

milk, without restoring this in the food, the lime will be obtained 
from its bones, which will thus lose gradually their strength and 
solidity, until they are no longer able to support the weight of the 
body. But if we give to the pigeon as food barley or peas, and 
to the cow barley-straw or clover, we will be able to sustain th . 
health of the animals ; for these materials abound in salts of 
lime.* 

Man and animals receive the constituents of their blood and of 
their bodies from the vegetable world ; and an Infinite Wisdom 
has so ordained, that the life and luxuriance of plants is strictly 
connected with the reception of the same mineral substances 
that are indispensable for the development of the animal organ- 
ism ; without the presence of the inorganic matters found in the 
ashes of plants, the formation of the germ, leaves, blossoms, or 
fruit, could not be effected. 

The amount of nutritive matters in the different kinds of cul- 
tivated plants is very unequal. The bulbous plants and roots 
approach each other much more nearly in their chemical consti- 
tuents than they do the seeds ; while the latter possess always 
an analogous composition. 

Potatoes, for example, contain from 75 to 77 per cent, of water, 
and from 23 to 25 per cent, of solid matter. By means of a 
mechanical process, we may divide the latter into 18 or 19 parts 
of starch, and 3 or 4 parts of a fibre resembling starch. Both of 
these added together weigh nearly as much as the dry potatoe. 
The two per cent, not accounted for consists of salts, and of the 
substance containing sulphur and nitrogen, known under the 
name of albumen. 

Beet contains from 88 to 90 per cent, of water. Five-and- 
twenty parts of dry beet contain very nearly the same elements 

*The laborers in the mines of South America, whose daily labor (per- 
haps the most severe in the world) consists in carrying upon their shoul- 
ders a load of earth of from ISO to 200 lbs. weight, from a depth of 450 
feet, subsist only upon bread and beans. They would prefer to confine 
themselves to bread, but tlieir masters have found that they cannot work 
so much on this diet, and they, therefore, compel them, like horses, to cat 
beans. — {DarwhVs Journal of Researches.) Beans are proportionally 
much richer in bone earth than bread. 



CONSTITUENTS OF PLANTS. 135 

as 25 parts of dry potatoes. In the beet there are IS or 19 part? 
of sugar and 3 or 4 parts of cellular tissue ; the two per cent, 
not accounted for consist partly of salts, and the remainder of 
albumen. 

Turnips contain from 90 to 92 parts of water. From 23 to 25 
parts of dry turnips contain 18 to 19 parts pectin, with very 
little sugar, 3 or 4 parts cellular tissue, and 2 parts salts and 
albumen. Sugar and starch do not contain nitrogen ; they exist 
in the plant in a free state, and are never combined with salts, or 
with alkaline bases. They are compounds formed from the car- 
bon of the carbonic acid and the elements of water. In the 
potatoe, these assume the form of starch, and in the turnip the 
form of pectin. 

In the seeds of cereals we find vegetable fibrin, a constituent 
containing sulphur and nitrogen ; in peas, beans, and lentils, we 
find CASEIN ; and in the seeds of oily plants, albumen and a 
substance very analogous to casein. Casein and albumen have 
the same composition as fibrin. 

Vegetable fibrin is accompanied by starch in the seeds of the 
cereals ; the latter body occurs with casein in leguminous 
plants ; but, in the oily seeds, its place is supplied by another 
body devoid of nitrogen, such as oil, butter, or a constituent 
resembling wax. 

It is obvious that we must furnish to plants the peculiar con- 
ditions necessary for the development of these constituents, 
according to our object in cultivation. In order to procure sugar 
or starch, we must supply the plant with other materials than 
we would do were our object to obtain the ingredients containing 
sulphur and nitrogen. 

In a hot summer, when the deficiency of moisture prevents 
the absorption of alkalies, we observe the leaves of the lime-tree, 
and of other trees, covered with a thick liquid containing a large 
quantity of sugar ; the carbon of this sugar must, without doubt, 
be obtained from the carbonic acid of the air. The generation 
of the sugar takes place in the leaves ; and all the constituents 
of the leaves, including the alkalies and alka ine earths, must 
participate in effecting its formation. Sugar does not exude from 
the leaves in moist seasons ; and this leads us to conjecture, thai 



136 ROTATION OF CROP5;. 

the carbon which appeared as sugar in the former case would 
have been applied in the formation of other constituents of the 
tiee, in the event of its having had a free and unimpeded circu- 
lation. When the soil is frozen in winter, there cannot be an 
absorption of alkalies by the roots ; but notwithstanding this, it 
cannot be doubted that during the day the evergreen and the 
leaves of fii's and pines must absorb continually from the air car- 
bonic acid, which will be constantly decomposed by the action of 
the light. When circulation is unimpeded, the carbon of this 
carbonic acid may perhaps be converted into wood or into other 
constituents of the plant ; but, in the absence of the conditions 
necessary for this conversion, it may now secrete resin, balsam, 
and volatile oils. In the generation of the sugar, or in that of 
resin and volatile oil in the firs and pines, all the constituents of 
the leaves must take part ; and hence we cannot suppose that 
their alkalies, their lime, &c., are either accidental, or that they 
are unnecessary to the exercise of this vital function. 

For the conversion of the carbon or carbonic acid into sugar, 
it is necessary that cei'tain conditions exist in the plant itself, in 
addition to the external circumstances (such as heat and air). 

We furnish the conditions essential to the formation of starch, 
or of sugar, when we supply to the leaves — that is, to the organs 
destined for the absorption and assimilation of the carbonic acid 
— their necessary constituents. 

The sap of such plants as are rich in sugar or in starch, and 
also the sap of most woody plants, contains much potash and 
soda, or alkaline earths. We cannot suppose that these are mere 
accidental ingredients ; on the contrary, we must believe that 
they serve some purposes of the plants, and that they assist in 
the formation of certain of their constituents. It has already 
been mentioned, that they exist in the plants in a state of com- 
bination with certain organic acids. These acids are so far 
characteristic of certain genera, that they are never absent from 
them. Hence the organic acids themselves must assist in some 
of the vital functions. Now, when it is remembered that unripe 
fruits, such as grapes, are unfit to eat on account of their acidity ; 
that these fruits possess the same power as the leaves of absorb- 
ing carbonic acid, and of giving off oxygen on exposure to light 



FORMATION OF SUGAR. 137 

(Saussure) ; and further, that the sugar increases on the diminu- 
tion of the acid ; we can scarcely avoid coming to the conclusion, 
that the carbon of tlie organic acid in the unripe fruit becomes a 
constituent of the sugar when it is ripe, and that, in consequence 
of the separation of oxygen and the assimilation of the constitu- 
ents of water, the acid passes into sugar. 

The tartaric acid in grapes, the citric acid in cherries and in 
currants, the malic acid in summer apples, which ripen on the 
trees, form in these plants the intermediate members of the pas- 
sage of carbonic acid into sugar ; and when there is a deficiency 
of proper temperature, or of the action of solar light, the changes, 
necessary for the conversion into sugar are not furnished, and the 
acids remain. 

In the fruit of the mountain ash, malic acid succeeds the tar 
taric acid at first present, or in other words, an acid poor in oxy 
gen succeeds one rich in that element; afterwards the malic acid 
in the berries disappears almost entirely, and in its place are 
found gum and mucilage, neither of which formerly existed in 
them ; and with the same reason that we consider that the carbon 
of the tartaric acid forms a constituent of the succeeding malic 
acid — and this few would be inclined to dispute — we suppose that 
the carbon of the acids passes over into the sugar which succeeds 
on their disappearance. 

It surely cannot be supposed that a plant assimilates carbonic 
acid, and that this carbonic acid is converted in the organism of 
the plant into tartaric, racemic, and nitric acids, merely for the 
purpose of being reconverted into carbonic acid. 

If then the view be confirmed, that the organic acids in culti- 
vated plants aid in the formation of sugar, it must be admitted 
that they are of equal importance in the production of all other 
non-azotized ingredients similarly composed. The formation of 
starch, of pectin, and of gum, does not take place immediately, that 
is, they do not arise at once from the union of the carbon of the 
carbonic acid with the constituents of water ; but a gradual con- 
version takes place, in consequence of the production of com- 
pounds that are always poorer in oxygen, and always richer in 
liydrogen. We cannot suppose that oil of turpentine could be 



13S ROTATION OF CROPS. 



formed without the existence of analogous intermediate memlk^rd 
of the series. 

Now, if the organic compounds rich in oxygen, viz. the acid?, 
be the means of producing the compounds poorer in this element, 
such as SUGAR, STAKCH, &c., then the alkalies and alkaline bases 
must be looked upon as the conditions essential for the formation 
of th' sp non-azotized constituents, because the acids existing in 
cultivated plants are generally in the form of salts and are rarely 
free. An organic acid may perhaps be formed without the pre- 
sence of these bases, but, in the absence of an alkali, or of a body 
possessing an analogous action, sugar, starch, gum, and pectin, 
cannot be formed in the organism of a plant. Sugar is not formed 
in those fruits and seeds in which the organic acids are free, that 
is, in which they do not exist as salts, as, for instance, citric acid 
in the lemon, or oxalic acid in the chick-pea. It is only in plants 
containing the acids combined with bases in the form of soluble 
salts, that sugar, gum, and starch, are produced. 

It is a matter of little consequence what value is attached lo 
the opinion now given of the part taken by alkaline bases in the 
process of vegetable life. But the following facts are of the great- 
est significance and value to agriculture, namely, that the newly- 
developed sprouts, leaves, and buds,* or in other words, those 
parts of the plants possessing the greatest intensity of assimilation, 
contain the greatest proportion of alkaline bases, and that the 

* 1000 parts of Firwood gave 3'2S parts of ashes. 
1000 " Fir-leaves " 62-25 
The ashes of the leaves of the fir amount to more than 20 times those in 
the wood freed from its bark 100 parts of the former contain : — (Hert- 
wig) 

Alkaline carbonates ) _ _ lO-"'! 

Comn-onsalt - - S ' ' '^ I V.-VO salts soluble in water. 
Sulphate of Potish - - 1 95 ( 

Silicate of Potash - - 390 J 

Carbonate of lime - - - 63'32 

" magnesia - - 1'86 

Phosphate of magnesia ) - g.g^ 

" lime 5 
Jjasic pcrphosphate of iron - O'SS 
Basic ptiosphate of alumina - 0-71 
Silica 10-31 



S6'30 compounc b insoluble in water 



IMPORTANCE OF ALKALIES. 139 

plants richest i'u sugar and in starch are no less distinguished for 
their quantity of alkaline bases and of organic acids. 

As we find sugar and starch accompanied by salts of an or- 
ganic acid ; and as experience proves that a deficiency of alka- 
lies causes a deficient formation of woody fibre, sugar, and starch ; 
and that, on the contrary, a luxuriant growth is the consequence 
of their abundant supply ; it is obvious that the object of culture, 
viz. a maximum of crops, cannot be obtained, unless the alkalies 
necessary for the transformation of carbonic acid into stai'ch and 
sugar are supplied in abundant quantity, and in a form fit for 
assimilation by plants.* 

* The acids — malic, tartaric, citric, oxalic, &c. — are generated in the 
organism of plants, and their carbon must be derived from carbonic acid. 

In plants these acids are found combined with potash, lime, and mag- 
nesia, in the form of salts, the smallest particles of which, when left to 
themselves, follow their own attractions ; this is indicated by their crys- 
tallization. 

1 here is no doubt that these compounds do not possess organic life, be- 
cause the active power observed in them is not vitality, but cohesion. 
The same must be the case with sugar, which crystallizes in a similar man- 
ner. 

We must presume that the smallest particles of the products formed 
from carbonic acid are subject to the powers acting upon them in the living 
plant, in the same way that a particle of carbonic acid is ; that, therefore, 
the carbon of oxalic acid, tartaric acid, &c., must possess the power of 
passing into a constituent of an organ endowed with life. 

The conversion of organic acids into organs may be followed with ease. 

If we suppose that 12 equivalents of carbonic acid, in the presence of a 
base, and by the action of light, loses the fourth part of its oxygen, in con- 
sequence of the action of vitality upon its elements, then oxalic acid would 
be produced. In its anhydrous state, we cannot conceive it to be formed 
from carbonic acid in any other way. 

C12O24 — 06=Ci 2 Oi 8^6 Eq. anhydrous oxalic acid. 

Oxalic acid does not exist in an anhydrous state. Hydrated oxalic acid 
cstitains one equivalent of water ; the oxalates of potash, lime, and mag 
nesia also contain water. Hydrated oxalic acid consists of — 

C 12 Oj 8 +H6 Os=Ci 2 Hg O2 4^6 Eq. hydrated oxalic acid. 

From this it may be observed that carbonic acid and hydrated oxalic acid 
contai.i the same quantity of oxygen. We can, therefore, suj)pose that 
hydrated oxalic acid has been formed from carbonic acid, to which a cer 
tain amount of hydrogen has been added. 

Ey the continued action of the same agents a new quantity of oxygen 
might become separated from the carbonic acid, in which case tartaric acid 



140 ROTATION OF CROPS. 

Every part and constituent of the body is obtained from plants. 
By the organism of the plants, are formed those compounds which 
serve for the formation of the blood ; there can be no doubt that 

or malic acid would result. By the separation of 9 equivalents of oxygen . 
tartaric acid would be produced ; the separation of 12 equivalents would 
produce malic acid. 

Hydrated oxalic acid C i 2 H g a 4 — 9=Ci2H80i5 =^3 Eq. tartaric acid. 
" " C12H6O24 — J 2^Ci aHgOi 2=3 Eq. malic acid. 

By the simple separation of water Irom the elements of malic acid citriu 
acid is produced ; we know that we can produce, by means of heat, aco- 
nitic acid from citric acid, and fumaric acid, or maleic acid, from malic 
acid. 

Malic acid C12 He O12 — H0=Ci2 H5 Oj i=3 Eq. citric acid. 
" C12H6O12 — 3HO=:Ci2H3 09 ==3 Eq. fumaric acid. 

Now we can view tartaric, citric, and malic acids as compounds of 
oxalic acid with sugar, with gum, with woody fibre, or with the elements 
of these : 

Tartaric Acid. O.xalic Acid. Dry Sugar of Grapes. 

2(Ci2H60is) = Ci20i8 + C12H12O12 

In such a manner, therefore, that the addition of new quantities of hydro- 
gen would enable all these acids to aid in the formation of sugar, starch, 
and gum. When this conversion is effected the alkalies in union with 
the acids must of course be liberated, and they will thus be rendered capa- 
ble of playing anew the same part. According to this view, it is quite 
conceivable that one equivalent of an alkali may enable 10, 20, or 100 
equivalents of carbon to pass into constituents of a plant; but the time 
necessary to effect the transformation will vary according to the amount 
of base present. 

If a perennial evergreen, by the help of a certain quantity of alkali, is 
able to assimilate a certain amount of carbon during the whole year, it will 
be necessary to convey to a summer plant four times the quantity of alkali, 
in order to enable it to assimilate the same amount of carbon in one-fourth 
the time. 

Gay-Lussac first observed that by the contact of an alkali, at a high tem- 
perature, with tartaric, citric, and oxalic acids, or sugar, woody fibre, &c., 
these substances were reconverted into carbonic acid. 

This mode of decomposition is quite the reverse of that which takes 
place in plants In the latter the elements of water unite with the com- 
pound of carbon (carbonic ac'd); and oxalic acid, tartaric acid, &c., are 
tlius produced, in consequence of a separation of ox tgen. But in 
the chemical process referred to, the elements of the water unite with the 
elements of oxalic and tartaric acids, &c., and they are reconverted into 
carbonic acid, in consequence of a separation of hydrogen. 

Without the development of any gas, tartaric and citric acids, in contact 
with alkali, even at a temperature of 400° F., are decomposed into oxalic 



IMPORTANCE OF ALKALIES. 141 

the nutritive parts of plants must contain all the constituents of 
the blood, and not merely one or two of them. 

It cannot be supposed that blood will be formed in the body of 
an animal, or milk in that of a cow, if their food fail in even ono 
of the constituents necessary for the sustenance of the vital func- 
tions. The compounds containing nitrogen and sulphur, as well 
as the alkalies and phosphates, are constituents of the blood ; but 
the conversion of the former into blood cannot be conceived with- 
out the presence and co-operation of the latter. 

According to this view, the power of any part of a plant to 
support the life of an animal, and to increase its blood and flesh, 
is in exact proportion to its amount of the organic constituents of 
the blood, and of the materials necessary for their conversion into 
blood — viz., of alkalies, phosphates, and fhlorides (common salt 
or chloride of potassium). 

It is highly worthy of observation, and of great significance to 
agriculture, that the vegetable compounds containing sulphur and 
nitrogen, which we have designated as the organic constituents 
of the blood, are always accompanied, in the parts of the plants 
where they occur, with alkalies and with phosphates. The juice 
of potatoes and of beet contains vegetable albumen accompanied 
by salts of alkaline bases, and by soluble phosphate of magnesia ; 
in the seeds of cereals and of peas, beans, and lentils, there are 
alkaline phosphates and earthy salts. 

The seeds and fruits, which are richest in the organic con- 
stituents of the blood, contain also the inorganic, such as the phos- 
phates, in large quantity ; other parts of plants, as the potatoe, and 
the various roots, which are proportionally so poor in the former 
ingredients, contain a much smaller quantity of the latter. 

The contemporaneous occurrence of both these classes of com- 

mA acetic acids. Anhydrous acetic acid contains carbon and the constitu- 
■;nts of water, in exactly the same relative proportions as woody fibre (Pe- 
1.IG0T), which also yields acetic acid under similar circumstances. 

These methods of decomposition have induced a distinguished French 
chemist to assume the existence of ready-formed oxalic acid in tartaric 
acid ; certainly its elements are present, besides those of a second body, 
which, like sugar, gum, and woody fiH'e, may be viewed as a compound 
of carbon with water. 



42 ROTATION OF CROPS. 



pounds is so constant, that it would be difficult to trace a case of 
more intimate connexion. It is extremely probable that the 
origin and formation of the organic constituents of the blood in 
the organism of plants is closely connected with the presence of 
phosphates. It must be supposed that the organic constituents of 
the blood will not be formed in a condition adapted for their con- 
version into blood, without the presence of alkalies and of phos- 
phates, which are found constantly to accompany them ; and this 
will be the case, even although carbonic acid, ammonia, and sul- 
phates as a source of sulphur, be presented to them in the most 
abundant quantity. But, even on the assumption that they could 
be generated in the organism of the plant, without the action of 
these substances, we cannot suppose that they could be converted 
into blood and flesh in the body of the animals, when the mineral 
constituents of the blood were absent from the vegetable given 
as food. 

But independently of these views, a rational farmer must en- 
deavor to effect the purpose desired, and in doing so he must act 
exactly as if the presence of the inorganic constituents of blood 
(the alkalies and phosphates) were indispensable for the produc- 
tion of the organic constituents ; for he must furnish to the plants 
all the materials necessary for the formation of the stem, leaves, 
and seeds. If he is desirous of making his land yield a maximum 
of blood and flesh, he must furnish to it in abundant quantity 
those constituents which the atmosphere cannot yield.* 

* When fresh arterial blood is evaporated to dryness and incinerated, 
ashes are obtained which yield to water salts of an alkaline reaction, but 
not any alkaline carbonates, for no effervescence is occasioned by tlie addi 
tion of an acid. These ashes consist of variable quantities of: — 

Phosphates of the alkalies. 

Phosphate of lime, 

Phosphate of magnesia, 

Basic perphosphate of iron 

Common salt, 

Sulphates of the alkalies. 
The ashes of seeds contain : — 



Phosphate of potash 
Phosphate of soda 



Red 


White 






Beans 


Wheat. 


W^HEAT. 


Rye. 


Peas. 


(vicia faia). 


Freseniiis. 


Will. 


Fresenius. 


Will. 


Buchner. 


• 36-51 


52-9S 


52 91 


52 -73 ) 


1 6S-59 


■ 3-213 


000 


9-27 


5-61 S 



IMPORTANCE OF ALKALIES. 143 

Starch, sugar, and gum contain carbon and the elements of 
water; but they are never combined with alkalies, nor do they 
contain phosphates. We can suppose that two specimens of the 
same plant, when supplied with the same amount of mineral food, 
may yet form very unequal quantities of sugar and of starch ; 
and that two equal surfaces of land prepared in exactly the same 
manner may bear two samples of barley, the one of which may 
yield half or double the weight of the seeds that the other does. 
But the excess of weight must depend upon the amount of unni- 
trogenous ingredients, and not on the constituents containing sul- 
phur and nitrogen ; for if the same quantity of the inorganic, 
constituents of blood be supplied to the soil, and if they enter into 
the plants, a corresponding quantity of the organic constituents 
of blood must be formed in the seeds, so that one cannot contain 
more than the other. A difference in the result can happen only 
when the one plant receives a less supply of nitrogen than the 
other, in a given time ; for when there is a deficiency of ammo- 
nia, a corresponding quantity of the inorganic constituents of the 
blood is left unemployed. 

When two species of plants are cultivated on a field of the 
same nature throughout, that species which generates the greatest 



Red 


White 






Beans 


Wheat. 


Wheat. 


Rye. 


Peas. i 


[vicia faba) 


Fresenius. 


Will. 


Fresenius. 


Will. 


Buchner. 


Phosphate of lime - 3-35 


5-06 


5-21 


10-77 


9-35 


Phosphate of magnesia - 19"61 


32-96 


26-91 


13-78 


19-11 


Perphosphate of iron - 3'04 


0-67 


1-88 


2-46 




Sulphate of potash - ) ^j. 
Common salt - - 5 ^^^^^s. 




2-98 


9-09) 
3-96 5 


1-84 


Silicate of potash 




0-34 




1-11 


Silica .... 0-15 


0-30 








^ri - - ■ ] 4-99 


8-03 


0-50 







In the above analyses, the phosphates of the alkalies in the peas and 
beans are contained and calculated as tribasic salts ; those in the seeds of 
the cereals, as bibasic. The ashes of the seeds cannot effervesce with 
acids, because they do not contain an alkaline carbonate ; in this respect 
they are similar to the ashes of blood ; and it may be observed that the 
salts in both are quite the same. If the ashes either of blood or of the 
seeds be exposed to air, they absorb caioouic acid and moisture ; the tri- 
basic phosphate becomes bibasic, and the third atom of alkali is converted 
into a carbonate. 



144 ROTATION OF CROPS. 



quantity of the organic constituents of the blood (compounds con- 
taining sulphur and nitrogen) will remove from the soil the 
greatest amount of inorganic constituents (phosphates). 

The one plant will exhaust a soil of these ingredients, but it 
may still remain in a good condition for a second kind of plant 
requiring a smaller quantity of phosphates, and may even be fer- 
tile for a third kind. 

Hence it happens that the greater development of certain parts 
of plants, such as the seeds, which contain much more of the or- 
ganic constituents of the blood than any of the other parts, exhausts 
and removes from the soil a much greater amount of phosphates 
than would be done by the culture of herbaceous plants, tubers, 
or roots, these being proportionally much poorer in the above in- 
gredients. It is further evident, that two plants growing together 
on the same soil will share its ingredients between them, if they 
both require in equal periods equal quantities of the same con- 
stituents. The ingredients taken up into the organism of one of 
the plants cannot be used by the other. 

If a given space of a soil (in surface and in depth) contains 
'^nly a sufficient quantity of inorganic ingredients for the perfect 
development of ten plants, twenty specimens of the same plant, 
cultivated on this surface, could only obtain half their proper ma- 
turity ; in such a case, there must be a difference in the number 
of their leaves, in the strength of their stems, and in the number 
of their seeds. 

Two plants of the same kind growing in close vicinity must 
prove prejudicial to each other, if they find in the soil, or in the 
atmosphere surrounding them, less of the means of nourishment 
than they require for their perfect development. There is no 
plant more injurious to wheat than wheat itself, none more hurt- 
ful to the potatoe than another potatoe. Hence we actually find 
that the cultivated plants on the borders of a field are much more 
luxuriant, not only in strength, but in the number and richness 
of their seeds or tubers, than plants growing in the middle of the 
same field. 

The same results must ensue in exactly a similar manner 
when we cultivate on a soil the same plants for successive years, 
instead of, as in the former case, growing them too closely to- 



EXHAUSTION OF SOILS. Z45 

gether. Let us assume that a certain soil contains a quantity of 
silicates and of phosphates sufficient for 1000 crops of wheat, then, 
after 1000 years, it must become sterile for this plant. If we 
were to remove the surface-soil and bring up the subsoil to the 
surface, making what was formerly surface-soil now the subsoil, 
we would procure a surface much less exhausted than the for- 
mer, and this might suffice to supply a new series of crops, but 
its state of fertility would also have a limit. 

A soil will naturally reach its point of exhaustion sooner the 
less rich it is in the mineral ingredients necessary as food for 
plants. But it is obvious that we can restore the soil to its 
original state of fertility, by bringing it back to its former com- 
position ; that is, by returning to it the constituents removed by 
the various crops of plants. 

Two plants may be cultivated side by side, or successively 
when they require unequal quantities of the same constituents, 
at different times; they will grow luxuriantly without mutual in- 
jury, if they require for their development different ingredients 
of the soil. 

The experiments of Saussure, and of many other philosophers, 
have shown that the seeds of beans, of Phaseolus vulgaris, of peas, 
and of garden cresses, germinate and even grow to a certain ex- 
tent in moist sand or moistened horse-hair ; but when the mine- 
ral substances contained in the seeds no longer suffice for their 
further growth, then the plants begin to droop ; they may even 
perhaps blossom, but they never bear seeds. 

Wiegmann and Polstorf allowed plants of various kinds to 
vegetate in a white sand previously treated with aqua fegia, and 
freed from the acid by careful washing.* Barley and oats grow- 
ing in this sand, on being properly treated with water free from 
ammonia, reached a height of 1| foot; they blossomed, but did 

*This sand contained in 1000 parts : — (Preisschrift, p. 2b. ,( 

- Silica 97y00 

Potash 3-20 

Alumina - . - . . 8 76 

Peroxide of iron - - - 31 5 

Lime 4-84 

Magnesia - - - 0-09 
8 



146 ROTATION OF CROPS. 

not come to seed, and withered after blossoming. Vetches reached 
a height of ten inches, blossomed, and put out pods, but they did 
not contain any seeds. 

Tobacco sowed in the sand, developed itself at first in the usual 
way, but from June to October the plants reached the height only 
of five inches; they had only four leaves and no stem. 

The analysis of the ashes of these plants, and also the analysis 
of their seeds, proved that although this sterile sand contained 
such a small quantity of potash and of soluble constituents, still 
it had yielded a certain quantity of these, and on this quantity the 
growth of the leaves and of the stem depended ; but it was im- 
possible that the plants could come to seed, because the con- 
stituents necessary for the formation of the seeds were entirely 
absent. 

Phosphoric acid was detected in the ashes of most of the plants 
growing in this sand, but its quantity corresponded only to that 
introduced to the soil in the seeds themselves. In the ashes of 
the tobacco plant, the seeds of which it is known are so small as 
to contain scarcely an appreciable quantity of phosphoric acid, 
not a trace of that acid could be detected. 

What theory distinctly indicated as the cause of the sterility 
of this sand, the experiments of Wiegmann and Polstorf com- 
pletely established. They took the same sand and prepared from 
it an artificial soil by the addition of salts manufactured in a 
laboratory (see Appendix) ; they then sowed in this soil the same 
plants, and saw that they flourished in the most luxuriant man- 
ner. The tobacco became three feet in height, and put forth 
many leaves ; on the 25th of June it began to blossom, and on the 
lOlh of August obtained seeds, from which on the 8th of Septem- 
ber ripe seed capsules with complete seeds were taken. In ex- 
actly the same way, barley, oats, buck-wheat, and clover grew 
luxuriantly, blossomed, and yielded ripe and perfect seeds. 

It is quite certain, that the growth of these plants in the for- 
merly sterile sand, depended upon the salts added to it. An equa. 
fertility for all plants is given to this artificial soil by the addition 
of certain substances which are absolutely necessary for the life 
of the plants, because they are present in the matured plant, and 
in its stem, leaves, and seeds. 



RESTORATION OF FERTILITY. 141 

Thus we are in a position to give to the most sterile soil a state 
of the greatest fertility for all plants, if we furnish to it the con-' 
stituents which they require for their growth. It would, indeed, 
neither repay the labor nor the expense to render fertile on those 
principles an absolutely sterile soil. But in our ordinary arable 
soils, which contain already many of these constituents, it suffices 
to supply the absent ingredients, or to increase those which are in 
deficient quantity. At the same time, by the art of farming, the 
soil must be put into a proper physical state, by which it is ren- 
dered accessible to moisture and to rain, and is fitted to enable 
the plants to appropriate these ingredients of the soil. 

Different genera of plants require for their growth and perfect 
maturity, either the same inorganic means of nourishment, al- 
though in unequal quantities and at different times, or they re- 
quire different mineral ingredients. It is owing to the difference 
of the food necessary for the growth of plants, and which must 
be furnished by the soil, that different kinds of plants exert mutual 
injury when growing together, and that others, on the contrary, 
grow together with gi'eat luxuriance. 

Very little difference is observed in the composition of the ashes 
of the same plants, even although they have grown on different 
soils. Silica and potash form invariable constituents in the straw 
of the Graminess ; and, in their seeds, there is always present 
phosphate of potash and phosphate of magnesia. A large quan- 
tity of lime occurs in the straw of peas and in clover. We know, 
further, that in certain kinds of plants, the potash is replaced by 
soda, and the lime by magnesia. 

It has been shown by the experiments of Boussingault,* that 
the five following crops grown in succession on an equal surface 
of the same field once manured, removed from the soil : — 

Ingredients of the soil 

1 Year crop of Potatoes (tubers without herb) - - 21G"S lbs. 

2 " " Wheat (straw and corn) ... - 3710 " 

3 " " Clover C20 " 

A u .. (Wheatt 4SS-0 " 

* I Fallow Turnips lOS'S " 

4 " " Oats (corn and straw) . - - . 215 " 

•Annales de Chimie et de Physique, t. i , p. 242 
t On a system of alternate crops. 



US ROTATION OF CROPS. 

Ingredients of the soil 
By a crop of Beetroot* (roots without leaves) ... 399"6 " 
" " Peas (peas and straw) . - - - - olS'O " 

" Rye 2S4-6 " 

" " Helianthus tuberosus . - - - - 660"0 " 



These numbers express the quantities c>f inorganic substances 
removed from the same soil by different plants, and carried away 
with the crops. They, therefore, prove that different plants take 
up into their organism, unequal weights of these ingredients of 
the soil. It is shown by a further consideration of the composi- 
tion of these ashes, that they differ essentially from each other 
with respect to their quality. 

One thousand parts of beet, turnips, or potatoes, yield by in- 
cineration 90 parts of ashes ; the latter are easily fusible, and 
contain a large quantity of carbonate of potash, and of salts with 
alkaline bases. Of these 90 parts, 75 parts ai'e soluble in cold 
water. 

Two thousand parts of dry fern yield also 90 parts of ashes ; 
but of these 90 parts none, or only a trace, is soluble in water 
(Berthiee). 

The ashes of wheat, barley, pea, and bean straw, differ in like 
manner in their composition. Equal quantities of their ashes 
contain very unequal amounts of ingredients soluble in water. 
There are certain ashes of plants wholly soluble in water ; 
others are only partially soluble, while certain kinds yield only 
traces of soluble ingredients. 

When the parts of the ashes Insoluble in water are treated 
with an acid (muriatic acid), this residue, in the case of many 
plants, is quite soluble in the acids (as for instance the ashes of 
beet, turnips, and potatoes) ; with other plants, only half the 
residue dissolves, the other half resisting the solvent action of the 

" In the above five-yearly rotation, wheat was introduced twice. In the 
second year the crop of wheat removed from the soil 371 lbs. and in the 
fourth year 45S lbs. of inorganic substances. This difference depends upon 
the unequal quantities of straw and corn in the crops of the two years. 
The weight of the straw and corn of one year was S790 lbs., in the other 
year it amounted to 10,8-58 lbs. The relative proportion of their ashes ia 
exactly the same. 



PLANTS DISTINGUISHED BY CERTAIN SALTS. 143 

acid ; while in the case of certain plants only a third, or even 
*ess of the residue is taken up by the acid. 

The parts of the ashes soluble in cold water consist entirely 
or" SALTS WITH ALKALINE BASES (poTASH AND soda) . The ingre- 
dients soluble in acids are salts of lime and magnesia ; and 
the residue insoluble in acids consists of silica. 

These ingredients being so different in their behavior to watei 
and to acids, afford us a means of classing tlie cultivated plants 
according to their unequal quantity of tliese constituents. Thus 
POTASH PLANTS are those the ashes of which contain more than 
half their weight of soluble alkaline salts : we may designate as 
lime PLANTS, and as silica plants, tliose in winch lime and silica 
respectively predominate. The ingredients thus indicated are 
those which form the distinguishing characteristics of the plants 
which require an abundant supply of them for their growth. 

The POTASH PLANTS include the chenopodia, arrach, worm- 
wood, &c. ; and amongst cultivated plants, the boet, mangel- 
wurzel, turnip, and maize. Tiie i.ime plants comprehend the 
lichens (containing oxalate of lime), the cactus (containing crys- 
tallized tartrate of lime), clover, beans, peas, and tobacco. 
Silica plants include wheat, oats, rye, and barley.* 



Salts of Potash S:ilts of Lime 

and Soda. and Mitgnesia. Silica. 

{Oatstraw with seeds (1) - - 34-00 'fOO Cy2 00 

Wheat-straw (2) - - - -22 00 7 20 6103 

Barlev-straw with seeds (1) -19-00 2")-70 5'y03 

Rye-straw (3) lS-63 16-52 63-89 



* The ashes of good meadow-hay (consisting of a mixture of the ai^hes 
of potash, lime, and silica plants), gave in 100 parts — (Haidi.ex) : 

Silica 00- 1 

Phosphate of lime . . - . lO'l 

Phosphate of peroxide of iron - - riO 

Lime 2-7 

Magnesia - - - . . - 8'6 
Gypsum - - - - - - 1-2 

Sulphate of potash ... - 2-2 

Chloride of potassium - - - - 1*3 

Carbonate of soda .... 2-0 

Loss 0-8 



ISO 



ROTATION OF CROPS. 



Lime 
Plants. 



Pot;\sh 
riant.s. 



Tobacco (Havannah) (4) 
(Dutch) (-1) - 
" (grown in an arti- 
ficial soil (1) 
Pea-straw (4) - - - 
Potatoe-herb (.'5) - - - 
^ Meadow-clover (1) - - 
Maize -straw (2) - - - 
'J'urnips - - - . - 
Beetroot (6) - - - - . 
I Potatoes (tubers) (6) - ■ 
[Helianthus tuberosum (7) ■ 



Suits of Potash 
and Soda. 

- - 24-34 

- - 2307 

- 29-00 



27 S2 

4 20 

39-20 

71-00 

SI -GO 
SSOO 
S5-S1 
84-30 



Salts of Lime 

and Magnesia. Silica. 

67-44 8-30 

62-23 15-25 



59-00 

63-74 
59-40 
56 00 
6 50 
18-40 
1200 
14-19 
15-70* 



1200 

7-81 
36 40 

4-90 
18-00 



Tliifi clussificaUon, liowover, is obviously only a very general 
one, and permits divi.sion into a great number of subordinate 
clas.ses ; particularly with re.spect to those plants in which the 
alkalies may be replaced by lime and magnesia. As far as we 
are aullioj'ized to judge by our present knowledge, a substitution 
of soda for potash lakes ])lace in our cultivated plants ; but it has 
not yet been o]>sorved, that in these plants the alkalies can be 
replaced by lime. 

The potatoe plant belongs to the lime plants, as far as regards 
the ingredients of its leaves, but its tubers (which contain only 
traces of lime) belong to the class of potash plants. With 
reference to the siliceous plants this difference of their parts is 
very marked. 

Barley must l^e viewed as a lime plant, when compared with 
oats or with wheat, in reference to their ingredients soluble in 
muriatic acid ; but it would be considered as a siliceous plant, if 
viewed only in reference to its amount of silica. Beet-root con- 
tains ))hospIiate of magnesia, and only traces of lime ; while the 
turnip contains phosphate of lime and only traces of magnesia. 

When we take into consideration the quantity of ashes, and 
fheir known composition, we are enabled to calculate whh ease, 
not only the particular ingredients removed from a soil, but also 



In the above analysis, the iigures reprcscr\r the chemists as under;— 

(1) Wiegmann and Polstort". I (5) Rerthi«r and Braconnot. 

(2) Saussure. | (6) Hiiischauor. 

(3) Fresenius. I (7) Rraconnct. 

(4) Hertwig. | 



EXHAUSTION OF SOILS BY CERTAIN PLANTS. ICl 

the degree in which it is exhausted of these by certain species 
of plants belonging to the potash, lime, or siliceous plants. 
This will be rendered obvious by the following examples. 

A soil, consisting of four Hessian acres, has removed from it 
by a crop of — 

Salts of potash Salts of lime, magnesia, 

and soda. and peroxide of iron. Silica, 

lbs. lbs. lbs. lbs. lbs. 

^^^-^t { \: tT ll'll ] 13«-^^ 3-So ] ^^-SS 260-05 

C In straw 4073) ^ „^ 3600) , 

^>^ Uncorn 42-05 5 ^^"^^ 21-82^ ^^ ^^ ^^^ ^^ 

Beet-root, without leaves - - 361-00 37-S4 

Heliiiiithus tuberosus - - - 556-00 104-00 

The same surface is deprived by these crops of the following 
quantity of phosphates* — 

* In the above numbers we have not an exact, but an approximate, pro- 
portion of the ingredients of the soil removed by the various crops. The 
analyses of the ashes have been used, as far as they are already made and 
known. The analysis of the ashes of the seeds and of the straw of wheat 
is by Saussure ; that of pea-straw by Hertwig; that of peas by Dr. Will ; 
that of the ashes of the straw and seeds of rye by Dr. Fresenius, of the beet- 
root by Hruschauer, and of Helianthus tuberosus by Braconnot. Exact 
and trustworthy results can only be obtained by estimating the ashes of 
the crops grown on a given surface, and by subjecting these ashes to 
analysis ; and not as in the above cases, in which the analyses were made 
upon the ashes of plants grown under different circumstances and in differ- 
ent situations. Boussingault, for example, obtained from pea-straw (from 
a crop heavily manured) 11-2 per cent, of ashes ; Saussure obtained only 8 
per cent, (in straw with seeds), and Hertwig only 5 per cent. These 
numbers change the absolute quantities, but have little or no influence on 
the relative proportions. 

The analyses by Sprengel of the ashes of vai^ous plants are quite inexact, 
and do not merit the slightest confidence. The ashes of the seeds of 
wheat, of peas, of beans, rye, &c., consist of phosphates, without any mix- 
ture of carbonic acid; these ashes do not contain silica. But Sprengel 
finds in peas 18 per cent, and in rye 15 per cent, of silica. The ashes of 
the seeds of rye contain 48 per cent., those of peas 34-23 per cent., of an- 
hydrous phosphoric acid; but Sprengel finds in peas only 4 per cent., in 
rye 8 per cent., of phosphoric acid. It is worthy of observation, that all 
the bases in the ashes of peas are present as tribasic phosphates, while in 
the ashea of rye and of wheat, they exist as bibasic salts. 



159 ROTATION OF CROPS. 





Helanthus 




Rve. 


tuberosus. 


Turnips.f 


77-05 


122 


37-84 



Peas.* Wheat. 

117 112-43 

According to the preceding views, plants must obtain from 
the soil certain constituents, in order to enable them to reach 
perfect maturity — that is, to enable them to bear blossoms and 
fruit. The growth of a plant is very limited in pure water, in 
pure silica, or in a soil from which these ingredients are absent. 
If there be not present in the soil alkalies, lime, and magnesia, 
the stem, leaves, and blossoms of the plants can only be formed 
in proportion to the quantity of these substances existing as a 
provision in the seed. When phosphates are wanting, the seeds 
cannot be formed. 

The more quickly a plant grows, the more rapidly do its 
leaves increase in number and in size, and therefore the supply 
of alkaline bases must be greater in a given time. 

As all plants remove from the soil certain constituents, it is 
quite obvious that none of them can render it either richer or 
more fertile for a plant of another kind. If we convert into 
arable land a soil which has grown for centuries wood, or a 
vegetation which has not changed, and if we spread over this 
soil the ashes of the wood and of the bushes, we have added to 
that contained in the soil a new provision of alkaline bases, and 
of phosphates, which may suffice for a hundred or more crops of 
certain plants. If the soil contains silicates susceptible of disin- 
tegration, there will also be present in it soluble silicate of 
potash or soda, which is necessary for the rendering mature the 
stem of the siliceous plants ; and, with the phosphates already 
present, we have in such a soil all the conditions necessary to 
sustain uninterrupted crops of corn for a series of years. 

If this soil be either deficient or wanting in the silicates, but 
yet contain an abundant quantity of salts of lime and of phos- 
phates, we will be enabled to obtain from it, for a number of years, 
Buccessive crops of tobacco, peas, beans, &c., and wine. 

But, if none of the ingredients furnished to these olants be again 
returned to the soil, a time must come when it can no longer 

*Heavily manured. t Heavily manured. 



EXHAUSTION OF SOILS. i;)3 

r.:rnish these constituents to a new vegetation ; when h must 
oecome completely exhausted., and be at last quite sterile, even 
for weeds. 

This state of sterility will take place earlier for one kind of 
plant than for another, according to the unequal quantity of the 
different ingredients of the soil. If the soil is poor in phosphates 
out rich in silicates, it will be exhausted sooner by the cultivation 
of \.'heat than by that of oats or of barley, because a greater 
quantity of phosphates is removed in the seeds and straw of one 
crop of wheat, than would be removed in three or four crops of 
oarley or of oats.* But if this soil be deficient in lime, the bar- 
ley will grow upon it very imperfectly. 

It is owing to the deficiency of these salts, so indispensabl* to 
the formation of the seeds, that it happens, however abundant may 
be the quantity of silicates, that in onr. year v/e may obtain nine 
times, in a second thrice, in a third twice as much corn as may 
grow on the same soil in another year. 

In a soil rich in alkaline silicito:-;, but containing only a limited 
supply of phosphates, the period of its exhaustion for these salts 
will be delayed if we alternate with the wheat plants which we 
cut before they have coins to .seed ; or, what is the same thing, 
with plants that remove from the soil only a small quantity of 
phosphates. If we cultivate on this soil peas or beans, these 
plants will leave, after the removal of the crop, a quantity of si- 
lica in a soluble state sufficient for a succeeding crop of wheat ; 
but they will exhaust the coil of phosphates quite as much as 
wheat itself, because the seeds of both require for their maturity 
nearly an equal quantity of these salts. 

We are enabled to delay the period of exhaustion of a soil of 
phosphate* by adopting a rotation, in which potatoes, tobacco, or 
clover, are made to alternate with a v;hite crop. The seeds of 
the plants now named are small, and contain proportionally only 
minute quantities of phosphates ; their roots and leaves, also, do 
not require much of these salts for their maturity. But it must 

* The weight of the ashes of a crop cf the seeds of wheat is to that in a 
rrop of oats as 31 :42'6, the phosphites contained in them as 26: 10; tha 
phosphates of the straw not being included in the calculation. 
8* 



{^4 ROTATION OF CROPS. 



be remembered, at the same time, that each of these has ren- 
dered the soil poorer, by a certain quantity of phosphates. Ey 
the rotation adopted, we have deferred the period of exhaustion, 
and have obtained in the crops a greater weight of sugar, starch, 
&c., but we have not acquired any larger quantity of the con- 
stituents of the blood, or of the only substances which can be con- 
sidered as properly the nutritious parts of plants. When the soi 
is deficient in salts of lime, tobacco, clover, and peas will no 
flourish ; whilst, under the same conditions, the growth of beet- 
root or turnips will net be impeded, if the soil, at the same time, 
contain a proper quantity of alkalies. 

When a soil contains silicates not prone to disintegrate, it may 
be able, in its natural state, to liberate by the influence of the at- 
mosphere, in three or four years, only as much silica as suffices 
for one crop of wheat. In this case, such a crop can only be 
grown on it in a three or four years' rotation, assuming that the 
phosphates necessary for the formation of the seeds exist in the 
soil in sufficient quantity. But we can shorten this period by 
working well the soil, and by increasing its surface, so as to make 
it more accessible to the action of the air and moisture, in order 
to disintegrate the soil, and to procure a greater provision of solu- 
ble silicates. The decomposition of the silicates may also be ac- 
celerated by the use of burnt lime ; bu: it is certain that, although 
all these means may enable us to ensure rich crops for a certain 
period, they induce, at the same time, an earlier exhaustion of 
the soil, and impair its i»atural state of ffcrlilit^/. 

If the proportion of alkali and of diica li;:.erated from the soil 
in the course of three or four years he sufficient only for one crop 
of wheat, we cannot in the interval, v/ithout injury to this crop, 
cultivate on the same soil any other plant ; because the alkali 
necessary for the grovvth of the latter cannot be applied to the use 
of the wheat. 

By examining the known proportion of alkali and of silica 
liberated by the disinte^gration of the silicates in their c-inversion 
into clay, and by the weathering of the latter itself,* we find that, 

•One equivalent of silica is liberattMl for every equivalent of potash 
•eparated from the constituents of an equivalent of felspar. In the straw 



WEATHERING OF SILICATES. 155 

for a given quantity of silica rendered soluble, a much larger 
amount of alkali is liberated than corresponds to the proportion in 
which both are taken up into the straw of the cereals. 

During the time of fallovv, which in this case must elapse be- 
fore two crops of wheat can be obtained, we may employ the ex- 
cess of alkalies in the culture of other plants requiring salts with 
alkaline bases without silica. Between these crops, therefore, we 
may grow mangel wurzel, or even potatoes, if we remove only 
the tubers of the latter, and allow the plant itself, which contains 
much silica, to remain on the field. 

In the preceding remarks, we have considered the changes in 
the nature and composition of a field on which a rotation of culti- 
vated plants has been carried on for a series of years. If this 
field contain an ordinary proportion of alkaline silicates, clay, 
lime, and magnesia, it will possess an almost inexhaustible pro- 
vision of alkalies, alkaline earths, and silica; with this dilfcrence, 
however, that they are not all in a fit state to be used by the plant 
at the same time. By the mechanical operations of the farm, and 
by chemical means (by the use of lime, &c.), we may shorten 
the time in which these obtain a form fitted for the vital functions 
of the plant ; but these matters do not suffice for its complete 
maturity. 

When phosphates and sulphates are absent from the soil, the 
plants growing on it cannot form seeds, because all seeds, without 
exception, contain compounds in which phosphoric acid and sul- 
phur are invariable constituents. Although all the other ingre- 
dients of plants be present in superabundance, the soil will become 
completely sterile, when the period arrives at which it can no 
longer furnish phosphates or sulphates to a new vegetation. 

We must suppose that, for the formation of the stem and herb, 
for the fixation of carbon, and for the production of sugar, starch, 
and woody fibre, a certain amount of alkalies (in the case of the 
potash-plants}, or an equivalent of lime (in the case of the lime- 
plants), is necessary. But we must bear in mind, at the same 
time, that the constituents of blood can be formed in the organism 



of wheat, oats, and rye, for 10 eq. of silica, there is only 1, or at tlie most, 
2 eq in combination with alkalies. 



158 ROTATION OF CROPS. 

of the plant only in quantity corresponding to that of the phos- 
phates, however abundantly ammonia or carbonic acid may be 
supplied. The production of the constituents of the juice con- 
taining sulphur and nitrogen is inseparably connected with the 
presence of these salts. 

Every soil upon which a weed attains maturity is fitted for 
culture if that weed yields, on incineration, alkaline ashes. 

The alkalies of these ashes arise from silicates, so that in addi 
tion to the alkalies, soluble silica must exist in the same soil 
Such a soil may contain a quantity of phosphates of lime and 
magnesia sufficient for potatoes and turnips, without on that ac- 
count being rich enough for crops of wheat. 

These considerations must show the great importance which 
onght to be attached to phosphates in the practice of agriculture. 
These salts are present in the soil only in small quantity, and 
therefore the greater attention should be paid to prevent its ex- 
naustion. 

In the limited but enormous extent of the ocean, whole worlds 
of plants and animals succeed each other. A generation of these 
animals obtain all their elements from plants, and the constituents 
of the organs of the animal after death assume their original form, 
and serve for the nourishment of a new generation of animals. 

The oxygen employed by the marine animals in the process of 
respiration, and removed from the air, dissolved in the water- 
(this air Contains from 32 to 33 volumes per cent, of oxygen, while 
atmospheric air contains only 21 per cent.), is restored again to 
the water, by the vital processes of marine plants. In the pro- 
ducts of the putrefaction of the carcases of the dead animals, 
their carbon is converted into carbonic acid, their hydrogen into 
water, and their nitrogen assumes again the form of ammonia. 

Thus, we observe that in the sea, a perpetual circulation takes 
place, without the accession or removal of an element, and this 
circulation is unlimited m its duration, alihcujh it may be m it.^ 
extent, by the finite quantity of nour.':;araent cont&ined in plants 
in a limited space. 

Willi respect to marine plar'ts, there Cannct l)e any discussion 
as to their rEceiving fciod by their roots in the form of humus. 
What nourislmient indeed can the thick roots of the giant sea- 



FOOD OF MARINE PLANTS. i57 

wnpr{ (h-aw from a naked rock, the surface of which does not suffer 
the slightest change — a plant which reaches a height of 360 feet 
f Cook), and one of which, with its leaves and twigs, atfords nour- 
ishment to tliousands of marine animals. Tiiese plants require 
ohviously only a fastening point in order to prevent a change of 
place, or an arrangement by which their small specific weight iai 
compensated ; they live in a medium which conveys the neces- 
sary nourishment to all their parts. Sea-water does not only con- 
tain carbonic acid and ammonia, but also phosphates, and earthy 
and alkaline carbonates, salts invariably found in the ashes of 
marine plants, and indispensable for their growth. 

All our knowledge tends to prove that the conditions necessary 
for the existence and duration of marine plants are the same as 
those upon which the existence of terrestrial plants depends. 

But terrestrial plants do not live like marine plants, in a me- 
dium containing all their elements, and surrounding every part 
of tlieir organism ; but their existence depends upon two media, 
the one of which, the soil, contains constituents which are absent 
from the other, the atmosphehe. 

How is it possible, we may well ask, that there ever could 
have been a doubt as to the part which the constituents of the soil 
took in the growth of the vegetable world ? Yet, there was a 
time when it was considered that the mineral constituents of 
plants were not necessary and essential to their existence ! 

The same circulation exists on the surface of the earth as in 
the sea ; there is an unceasing change — a perpetual destruction 
and re-establishment of equilibrium. Practice in agriculture has 
taught us that the amount of vegetable matters on a given sur- 
face increases with the supply of certain substances, which were 

ORIGINAL CONSTITUENTS OF THE SAME SURFACE OF THE SOIL, and 

had been removed from it by means of plants. The excrements 
of men and of animals arise from plants; they are exactly the 
materials which, during the life of the animal, or after its death, 
obtain again the same form that they possessed as constituents of 
the soil. 

We know that the atmosphere docs not contain these materials, 
and that it does not replace them ; we know further that, by their 
removal from the soil, an inequality of production is occasioned 



.58 ROTATION OF CROPS. 

and, finally, even a want of fertility ; but that, by the restoration 
of these materials, the fertility may be sustained, and even in- 
creased. 

After so many striking proofs respecting the origin of the con 
stituents of plants and of animals, and of the use of alkalies, of 
phosphates, and of lime, can we entertain the slightest doubt of 
the principles upon which a rational system of agriculture must 
depend ? 

Does the art of farming, then, depend upon anything else than 
the restoration of a disturbed equilibrium ? 

Is it conceivable, that a rich fertile land, with a flourishing 
trade, which has for centuries exported the products of its soil in 
the form of cattle and of corn, can retain its fertility, if the same 
trade do not restore to its land, in the form of manure, the con- 
stituents abstracted from it, and which cannot be replaced by the 
atmosphere ? In such a case, would not the same fate await this 
land as that which befel Virginia, upon the soil of which wheat 
and tobacco can no longer be cultivated ? 

In the large towns of England, the products of English as well 
as of foreign agriculture are consumed ; and to supply this great 
consumption, the constituents of the soil necessary to the plants 
are removed with them, from an immense surface of land, to 
wliich they are not again returned. The domestic arrangements 
peculiar to the English render it difficult, perhaps even impossi- 
ble, to collect the immense quantity of phosphates (the most im- 
portant ingredients of the soil, although present in it in small 
quantity), which are daily sent into the rivers in the form of urine 
and of solid excrements. We have seen upon the fields of Eng- 
land exhausted of their phosphates, the most beneficial effects pro- 
duced upon the crops by the introduction of bones (phosphate of 
lime) from the Continent ; in some cases, the crops on the soil 
, were doubled by the use of this manure, as if by a charm. 

But if this exportation of bones be continued on the same scale 
as at present, the German soil will become gradually exhausted ; 
and the loss will be perceived to be greater than at first is ap- 
parent, when it is considered tliat a single pound weight of bonca 
contains as much pliosphoric acid as a whole hundred-weight 
of corn. 



WASTE OF MANURE IN ENGLAND .: , 

Thousands of hundred weights of phosphates flow ariiiual' y ir.to 
he sea with the Thames, and with other of the British rivers. 

Thousands of hundred-weights of the same materials, arising 
from the sea, annually flow back again into that land in the form 
of guano. 

In the alchemistical era, the imperfect knowledge of the pro- 
perties of matter gave rise to the supposition, that metals, such • s 
gola, could be developed by seeds. Crystalline forms, and the 
ramifications which they assume, appu;ared to alchemists to be the 
leaves and branches of metallic plants, and their great endeavors 
were to find an earth fitted for the peculiar growth and develop- 
ment of their seeds. Without there being any apparent nourish- 
ment given to a seed, it was seen to grow to a plant, which put forth 
blossoms and seeds. This led to the belief, that could the seeds 
of metals be procured, similar hopes of their reaching maturity 
might be entertained. 

Such ideas could only belong to a time when scarcely anything 
was known of the nature of the atmosphere, and when there was 
not a conception of the part taken by the earth and air in the vital 
processes of plants. 

The chemistry of the present day exhibits the elements of 
water ; it can even prepare this water with all its properties from 
their elements ; but it cannot manufacture these elements — it can 
only prepare them from water. The newly-formed water, Avhich 
has been artificially prepared, was water previously to the separa- 
tion of its elements. 

Many of our farmers, like to these alchemists of old, in search- 
ing after the philosopher's stone, look now to find the wonderful 
seeds ; for they expect tiiat their land should bear a hundred- 
fold, without supplying to it any food, even although this land 
is scarcely rich enough to henv the plants usually cultivated 
on it ! 

The experience of centuries or of thousands of years is not 
sufficient to protect them from the new fallacies which are con- 
stantly arising ; the power of resisting the effects of credulity or. 
superstition can only be obtained from a knowledge of true scien- 
tific principles. 

In the first stage of the philosophy of nature, it was supposed 



160 ROTATION OF CROPS. 



ihat the organic kingdom was developed from water alone ; then 
it was considered that both water and air were necessary ; and 
now we know, with the greatest certainty, that the soil furnishes 
other important conditions, which must be added to the former, 
otherwise plants will not obtain the power of propagating and 
of multiplying themselves. 

The quantity of food for plants in the atmosphere is limited, 
but still it must be sufficient to cover the surface of the earth with 
a rich vegetation. 

In the tropics, and in those regions of the earth where a favor- 
able soil, moisture, light, and an elevated temperature — the usual 
conditions of fertility — are combined, the vegetation is scarcely 
confined by the space on which it grows ; there, when the soil is 
deficient, the bark and branches of dead plants soon form soil for 
succeeding ones. It is obvious, therefore, that there is no 
deficiency of atmospheric food for the plants of these regions, 
and there can be none for our own cultivated plants. 

The constant movement to which the atmosphere is subjected, 
causes an equal distribution of the gaseous food necessary for 
the growth of plants, so that the tropics do not contain more 
of it than the cold zones ; and yet, how different appear;? 
to be the power of production of equal surfaces of land in these 
regions ! 

All plants of tropical regions, sucli as the sugar-cane, the 
palms bearing wax and oil, contain, in comparison with our own 
cultivated plants, only a small quantity of the constituents of 
blood necessary for the nourishment of animals. The produce 
in tubers, of an acre of potatoes, growing, as in Chili, to the 
height of a tall bush, would scarcely suffice to prolong the life 
of an Irish family for a day (Darwin). The nutritious plants 
which are the objects of culture, are only a means for generating 
the necessary constituents of tlie blood. If the ingredients of the 
soil indispensable to their formation be absent from it, the consti- 
tuents of the blood cannot be formed in the plants, although it is 
possible that wood, sugar, or starch, might be produced under 
such circumstances. If we desire to produce from a given sur- 
face more of these constituents of the blood, than the plants 
growing on it could receive from the atmosphere or from the soil 



TROPICAL VEGETATION. 151 

in their natural wild and normal condition, we must procure an 
artificial atmosphere, and we must add to the soil the ingredients 
in which it is deficient. 

Very unequal quantities of nourishment must be furnished to 
different plants in a given time, in order to procure a free and 
unimpeded growth. On arid sands, simple calcareous soils, or on 
naked rocks, few plants flourish, and those that do are generally 
perennial. These, growing slowly, require only small quanti- 
ties of mineral ingredients, so that soils sterile for other kinds of 
plants are still able to furnish to them mineral ingredients in 
sufficient quantity. The annuals, particularly summer plants, 
reach complete maturity in comparatively a short time, so that 
they do not flourish on a soil poor in the mineral substances ne- 
cessary for their growth. 

The food contained in the atmosphere does not suffice to 
enable these plants to obtain their maximum of size in the short 
period of their life. If the object of culture is to be attained, 
there must be present in the soil itself an artificial atmosphere 
of carbonic acid and ammonia, and this excess of nourishment, 
which the leaves cannot get, must be conveyed to corresponding 
organs existin": in the soil. 

But the ammonia with carbonic acid does not suffice to enable 
itself to become a constituent- of a plant fit for the food of animals. 
Albumen cannot be formed without alkalies, and vegetable fibrin 
and casein cannot be produced without the aid of phosphoric acid 
and of earthy salts. We know that phosphoric acid is indis- 
pensable for the production of the seeds of our cereals and culi- 
nary vegetables, although the same acid is found in large quan- 
tily in an excrementitious form in the bark of woody plants. 

How very different, in comparison with summer plants, are 
the characters of evergreens, of mosses, ferns, and pines ! 
During every part of the day, both in summer and in winter, 
they absorb by their leaves carbonic acid, which the sterile soils 
cannot yield : their fleshy leather-like leaves retain with great 
tenacity tiie water absorbed, and lose very little of it by evapora- 
tion, in comparison with other plants. And yet how very small; 
is the quantity of mineral substances which they abstract from 
the soil during the whole year of almost perpetual growth, when 



/62 ROTATION OF CROPS. 



we compare it with the quantity removed from the soil in three 
months by a crop of v/heat of equal weight ! 

It follows, then, from the preceding observations, that the ad- 
vantage of the alternate system of husbandry consists in the fact 
that the cultivated plants abstract from the soil unequal quantities 
of certain nutritious matters. 

A fertile soil must contain in sufficient quantity, and in a form 
adapted for assimilation, all the inorganic materials indispensable 
for the growth of plants. 

A field artificially prepared for culture, contains a certain 
amount of these ingredients, and also of ammoniacal salts and de- 
caying vegetable matter. The system of rotation adopted on such 
a field is, that a potash-plant (turnips or potatoes) is succeeded by 
a silica plant, and the latter is followed by a lime-plant. All these 
plants require phosphates and alkalies — the potash-plant requiring 
the largest quantity of the latter and the smallest quantity of the 
former. The silica plants require, in addition to the soluble silica 
left by the potash plants, a considerable amount of phosphates ; 
and the succeeding lime-plants (peas or clover) are capable of 
exhausting the soil of this important ingredient to such an extent, 
. that there is only sufficient left to enable a crop of oats or of rye 
to form their seeds. 

The number of crops which may be obtained from the soil de- 
pends upon the quantity of the phosphates, of the alkalies, or of 
lime, and the salts of magnesia existing in it. 

Tiio existing provision may suffice for two successive crops 
of a potash or of a lime-plant, or for three or four more crops of 
a silica plant, or it may suffice for five or seven crops of all taken 
together ; but after this time, all the mineral substances removed 
from the field in the form of fruit, herbs, or straw, must again be 
returned to it ; the equilibrium must be restored, if we desire to 
retuin the field in its original state of fertility. 

This is eflectcd by means of manure. It may be assumed that 
the soil receives again, in the roots and stubble of the cereals, or 
• in the fidlen leaves of trees, as much carbon as its humus yielded 
in t!ie form of carbonic acid at the commencement of a new vege- 
tation ; in like manner, the herb of the potatoe and the roots of the 
clover remain in the soil. The remains of these plants enter into 



RESTORATION OF THE INGREDIENTS OF THE SOIL. 163 



decay during winter, and thus furnish to the young phint a new 
source of carbonic acid. The soil, therefore, is not exhausted of 
its humus by the cultivation of these plants. 

It may also be deduced from theoretical considerations, that the 
soil receives during the life of the plants as much, or perhaps 
even more, of carbonaceous materials as it yields to them ; and 
that the soil is enriched in these matters by the process of secre- 
tion proceeding at the surface of the fibres of the root ; the mat- 
ters tlius secreted enter into decay during winter, and pass into 
humus. 

Physiologists differ in their opinions with regard to the pro- 
cesses of secretion and excretion by plants ; some affirm that these 
processes do exist, while others deny their existence ; so that, at 
this moment, the opinions are divided on the subject. But still, 
no one denies that the oxygen separated by the leaves and green 
parts of plants ought to be considered as an excrement. In the 
act of vital activity, the plants assimilate the carbon of carbonic 
acid, and the hydrogen of water, making them constituents of their ^ 
organs, while they separate part of the oxygen with which these 
elements were combined. 

In the blossoms we find volatile oils, compounds rich in carbon 
and in hydrogen, and which are not further employed in any of 
the vital processes : out of the bark we see flowing resin, balsam, 
and gum ; and out of the leaves, sugar and mucilaginous sub- 
stances. 

Oxygen is not separated from the surface of the bark, roots, or 
other parts that are not green ; but, on the contrary, these parts 
separate substances rich in carbon which have been generated by 
the vital processes of the plant, but have not experienced any 
further change. 

When we compare the barks of the fir,* pine, beech, or oakj 



* Ashes of Wood of Ashes of the Be. 's 

the Fir. of the Fir. 

Hertwg. Hertwig. 

1000 wood gave 328 ashes. 1000 bark gave 17 '85 ashes 

{Carbonate of soda - - 7-42 

Carbonate of potash -1130 Soluble saits 2-95 
Chloride of sodium > -p^^^^g^ 
Sulphate of pota'-h 



164 



ROTATION OF CROPS. 



with their sap and wood, we find that they differ essentially from 
each other, both in their composition and characters. 

True wood yields only one-fourth to two per cent, of ashes, 
while the bark of the oak, fir, willow, and beech, gives 6, 10, to 
15 times more. The ashes of wood and of the bark have a very 
different composition. The inorganic ingredients of the bark 
are obviously inorganic substances expelled by the living or- 
ganism. 

The same reasoning holds good in the case of the organic sub- 
stances as it does in the case of the bark. The bark of the cork- 
tree contains nearly half its weight of fats, or of fatty substances, 
which we also find present, although in smaller proportion, in the 
bark of firs and pines. The solid material (insoluble in alcohol 
or ether) of these barks is entirely different from woody fibre. 
The barks of firs and pines are completely soluble in potash leys, 
forming a liquid of a dark brown color, which yields, on the ad- 
dition of an acid, a precipitate strongly resembling the substance 
called humic acid. But wood is not attacked by potash ley. 

These barks are in so far true excrements, that they arise from 
living plants, and play no further part in their vital functions ; 
they may even be removed from them, without thereby endanger- 
ing their existence. It is known that certain trees throw off an- 
nually their barks : this circumstance, viewed in its proper light, 
shows that, during the formation of certain products formed by the 
vital processes, materials arise which are incapable of experien- 
cing a further change. 





Ashes of Wood of 




Ashes of the Bark 




the Fir. 




of the Fir. 




Hkrtwio. 




Hertwiq. 




' Carbonate of lime - - 50 94 


. 


- 64-98' 






Magnesia . . - . 5-60 


. 


- 0-93 






Phosphate of lime - - 3-43 


- 


- 5-03 






" magnesia- 2'90 


- 


- 4 IS 




isoluble 
Suits. 


" manganese Traces 


. 


- 


Insolvble 
' Salts 9 ?-05 


" peroxide of ? ,.q. 
iron - ) 




- 1 04 












" alumina - 115 


- 


- 2 '42 






Silica - - - 13-37 


- 


- 17-2S 






^Loss ... - ;2-26 


- 


- 1-79. 





100-00 



10000 



BARK VIEWED AS EXCREMENTITIODS IfiS 



There is every reason to believe that this separation takes place 
over the whole surface ; it is observed not only on the stem, but 
also on the smallest twigs ; and hence we must conclude that the 
same excretory process goes on in the roots. 

When a branch of a willow is allowed to vegetate in rain-water, 
the latter assumes gradually a dark-brown color. The same 
phenomenon is observed in bulbous plants (such as hyacinths) 
allowed to grow in pure water. It therefore cannot be denied 
that excrements are actually separated by plants, although it is 
very possible that they do not all separate them in the same 
degree. 

It is generally admitted by farmers, as the result of experience, 
that a soil is enriched in organic matters by the culture cf peren- 
nial plants, such as sainfoin and lucerne, which are distinguished 
for the extensive ramification of their roots and strong growth of 
their leaves ; the cause of their enriching power will perhaps be 
explained from the above remarks. 

We cannot effect the formation of ammonia on our cultivated 
land, but it is in our power to obtain an artificial production of 
humus: this must be viewed as one of the objects of a system of 
rotation, and as a second cause of the advantage arising from it. 

By sowing a field with a fallow crop, such as clover, rye, 
lupins, buck-wheat, &c., and by ploughing and incorporating with 
the soil, the plants, when they have nearly come to blossom, we 
procure to the young plants of a new crop sown on the field a 
maximum of nourishment and an atmosphere of carbonic acid, in 
consequence of the decay of the preceding crops. Ail the nitro- 
gen drawn from the atmosphere by the preceding plants, and all 
the alkalies and phosphates received from the soil, now serve to 
cause a luxuriant growth to the plants which succeed. 



166 ON MANURE 



CHAPTER XII. 

On Manure. 

In order to obtain clear ideas on the value and action of ani- 
mal excrements, it is most important to bear in mind their origin. 
It is well known, that when a man or an animal is deprived of food, 
he becomes emaciated, and his body diminishes in weight from 
day to day. This emaciation becomes visible after a k\v days ; 
and in the case of persons who are starved to death, their fat and 
muscular substance disappear, their body becomes empty of 
blood, and at last nothing remains except skin and bones. 

On the other hand, the weight of the body does not alter, even 
though supplied with sufficient food ; for in the body of a healthy 
man there is neither a marked increase nor diminution of weight 
from one twenty-four hours to another. 

These phenomena prove with certainty that a change proceeds 
in the rganism of an animal during every moment of its life ; 
and a part of the living substance of the body passes out from it 
in a state more or less changed. The weight of the body, there- 
lore, would decrease continually, if the parts separated or changed 
were not again prepared and replaced. 

The restoration and replacement of the original weight is 
effected by means of food. 

A man or an animal consumes daily a certain number of oun- 
ces, or of pounds of bread, flesh, or other nutritive substances, 
so that in a year he consumes an amount of food of a mucb 
greater weight than that of his own body. He takes in the food 
a certain quantity of carbon, hydrogen, oxygen, nitrogen, and 
sulphur, as well as a very considerable quantity of mineral in- 
gredients, which we have learned to know as the ashes of food. 

What, it may be asked, has become of all these constituents 
of the food, to what purposes have they been applied, and in 



FOOD UNDERGOES COMBUSTION IN THE BODY. r7 

what form have they been expelled from the body ? Carbon and 
hydrogen have been furnished to the body, and yet the weight of 
the body, with respect to these elements, has not increased : the 
body has received in the food a quantity of alkalies and of phos- 
phates, but still the amount of these substances in our body has 
not been rendered greater. 

These questions are easily solved, when it is considered that 
the food does not supply the only conditions necessary for the 
support of the viiui processes, for there are other conditions 
which distinguish animals essentially from plants. 

The life of an animal is essentially connected with a continual 
introduction into its system of the oxygen contained in air. 
Without ui/ and oxviren, animals cannot exist. In the process of 
respiration, a certain quantity of oxygen is introduced into the 
blood by means of the lungs. The air which we respire contains 
this oxygen, and yields it to the constituents of the blood ; the 
blood of an adult man removes from the air, at each respiration, 
about two cubic inches of oxygen. A man consumes in 24 hours, 
from 10 to 14 ounces of oxygen — in a year, hundreds of pounds ; 
what then becomes of this oxygen? We take into our bodies 
pounds weight of food and pounds weight of oxygen, and never- 
theless the weight of our body either does not increase to any 
sensible extent, or it does so in a much smaller proportion than 
corresponds to the food : in certain individuals (in old age) it 
experiences a continued reduction. 

It must be obvious, that this phenomenon is explicable only on 
the supposition that the oxygen and the constituents of the food 
exercise on each other in the organism a certain action, in con- 
sequence of which both disappear from the body. This is actu- 
ally the case ; for none of the oxygen respired as a gas into the 
body remains in it ; it is separated in the form of carbonic acid 
and water. The carbon and hydrogen, which have combined 
with the oxygen, are derived from the organism ; but as these ele- 
ments of the body are obtained from the food, it may be said, 
thaf, in their final form, all the elements of food capable of uniting 
with oxygen are converted, in the living body, to oxygenized 
compounds, or, what expresses the same thing, they enter into 
combustion. 



,M ON MANURE. 



When bread, flesh, potatoes, hay, or oats, are burned in a com- 
mon fire-place, with an ordinary draughl;, but perfectly exposed to 
the entrance of the air, the carbon of these substances is con- 
verted into carbonic acid, their hydrogen into water, their nitro- 
gen is set at liberty in the form of ammonia, and their sulphur 
assumes the form of sulphuric acid, so that at last nothing re- 
mains except the mineral ingredients of these substances in the 
form of ashes. In the form of volatile products, we obtain car- 
bonic acid, carbonate of ammonia, and water, and besides these 
(if the combustion be incomplete), smoke or soot ; in the incom- 
bustible residue we obtain all the salts contained in tiie food. 

When water is poured over these ashes, the alkalies dissolve, 
and also the soluble phosphates, common salt, and sulphates ; 
the residue, insoluble in water, contains salts of lime and magne- 
sia, and silica, if the substance burned containe-d the latter sub- 
stance. 

Exactly the same process ensues in the bodies of animals. 
Through the skin, and by means of the lungs, the carbon and 
hydrogen of the food are expelled in their final form of carbonic 
acid and water ; all the nitrogen of the food is collected in the 
urinary bladder in the form of urea, which by the simple union of 
the elements of water is converted into carbonate of ammonia. 

When the body regains its original weight, exactly as much 
carbon, hydrogen, and nitrogen, as it took in the food, must have 
been expelled from it. It is only in youth, and in the process of 
fattening, that an increase in weight takes place, and that, there- 
fore, part of the constituents of the food remains in the body : in 
old age, on the contrary, the weight decreases, that is, more is 
separated from the body than enters into it. 

The nitrogen of the food is, therefore, daily expelled by the 
urine in the form of urea and of compounds of ammonia. The 
faeces contain the unburned substances of the food, such as the 
woody fibre, chlorophyl,* and wax, which have suffered no 
change in the organism ; the carbon, hydrogen, and nitrogen of 
bese substances are very small in quantity, in comparison with 

* Chlorophyl is the green coloring matter of the leaves and other parts 
rsf plants. 



ASHES OF FOOD OBTAINED FROM SOILS. 16v 

.hat in the food. The mixture of these indigestible materiala 
with the secretions may be compared to the smoke and sooi 
produced when food is imperfectly' burned in a common fire- 
place. 

It has been shown, by an examination of faeces and of urine, that 
the mineral ingredients of the food, the alkalies, salts, and silica, 
are eliminated in these excrements. Urine contains all the solu- 
ble mineral substances of the food, while the faeces contain the 
ingredients insoluble in water. As the food is burned in the 
body just as it would be in a fire-place, the urine may be said to 
contain the soluble salts of the ashes, and the faeces the insoluble 
salts. — (See Appendix.) A horse 

CONSUMES OK INGREDIENTS OF THE SOIL — AND THE EXCREMENTS RETURN — 

Ounces of Ashes. Ounces of Ashes, 



In ISlbs. hay* . 


18-61 } 


In urine 


. 3-51 > 


In 4-54 oats 


2-46 > 21-49 


In faeces 


. 18.36 > 


In its drink . 


0-42 > 

A COW — 






In 30 lbs. of potatoes . 


. 6-67) 


In urine 


. 12-29 


In hay 


. 20-20 V 28-47 


In faeces 


. 16-36 


In its drink . 


. 1.6 S 


In milk 


1-80 



30-45 

These analyses show, as nearly as can be expected from ex- 
periments of this kind, that all the constituents of the ashes of 
the food are again obtained, without alteration, in the solid and 
liquid excrements of the horse and cow. The action produced 
upon our fields, by the liquid and solid excrements of animals, 
ceases to be mysterious or enigmatical, as soon as we have at- 
tained a knowledge of their mode of origin. 

The mineral ingredients of food have been obtained from our 
fields, having been removed from them in the form of seeds, 
of roots, and of herbs. In the vital processes of animals, ihe 
combustible elements of the food are converted into compounds 
of oxygen, while the urine and the faeces contain the constituents of 
the soil abstracted from our fields ; so that, by incorporating 
these excrements with our land, we restore it to its origmal state 
of fertility. If they are given to a field deficient in ingredients 
necessary for the growth of plants, it will be rendered fertile for 
all kinds of crops. 

• Boussingault, Annales de Chiinie et de Physique, Ixxi 
9 



1% ON MANURE. 



A part of the crop taken from a field is used in feeding and 
fattening animals, which are afterwards consumed by man. 
Another part is used directly in the form of potatoes, meal, or 
vegetables ; while a third part, consisting of the remnants oi 
plants, are employed as litter in the form of straw, &c. It is evi- 
dent that all the constituents of the field removed from it in the 
form of animals, corn, and fruit, may again be obtained in the 
liquid and solid excrements of man, and in the bones and blood 
of the slaughtered animals. It altogether depends upon us to keep 
our fields in a constant state of composition and fertility by the 
careful collection of these substances. We are able to calculate 
how much of the ingredients of the soil are removed by a sheep, 
by an ox, or in the milk of a cow,* or how much we convey 
from it in a bushel of barley, wheat, or potatoes. From the 
known composition of the excrements of man, we are also able to 
calculate how much of them it is necessary to supply to a field 
to compensate for the loss that it has sustained. 

It is certainly the case, that we could dispense with the excre- 
ments of man and animals, if we were able to obtain from other 
sources the ingredients on which depends all their value for agri- 
culture. It is a matter of no consequence whether we obtain 
ammonia in the form of urine, or in that of a salt from the pro- 
ducts of the distillation of coal ; or whether we obtain phos- 
phate of lime in the form of bones, or as the mineral apatite. The 
principal object of agriculture is to restore to our land the sub- 
stances removed from it, and which the atmosphere cannot yields 
in whatever way the restoration can be most conveniently effected, 

* 1000 parts of milk yielded, by incineration — 

I. • 67-7 Residue 

II 49-0 " 

100 parts of the ashes of the milk consisted of: — 



Phosphate of lime . 


, 47-14 


50-81 


" magnesia 


. S.57 


9.45 


Perphosphate of iron 


. 1.43 


104 


Chloride of potassium . 


. 29-33 


2703 


Couinoii salt 


. 4-89 


5- 


So'ia 


. 8 57 


IV'M 




9C1-9S 


1000 00 



PHOSPHATES OF FOOD RESTORED BY EXCREMENTS. Vn 

If the restoration be imperfect, the fertility of our fields, or of 
the whole country, will be impaired ; but if, on the contrary, we 
add more than we take away, the fertility will be increased. 

The importation of urine or of solid excrements from a foreign 
land, is quite equivalent to the importation of com and cattle. 
All these matters, in a certain time, assume the form of corn, 
flesh, and bones ; they pass into the bodies of men, and again as- 
sume the same form which they originally possessed. The only 
true loss that we experience, and that we cannot prevent, on ac 
count of the habits of our times, is the loss of the phosphates, 
which man carries in his bones to the grave. The enormous 
quantity of food, which man consumes during the sixty years of 
his life, and every constituent of it that was derived from our 
fields, may again be obtained and restored to them. It is quite 
certain, that it is only in the bodies of our youth, and in those of 
orrovving animals, that a certain quantity of phosphate of lime is 
retained in the bones, and of alkaline phosphates in the blood. 
With the exception of this extremely small proportion, in com- 
parison with the actual quantity existing in the food, all the suits 
with alkaline bases, and all the phosphates of lime and magne- 
sia, which animals daily consume in their food, — in fact, there- 
fore, all the inorganic ingredients of the food, — are again obtained 
in the solid and liquid excrements. Without even instituting an 
analysis of these excrements, we can with ease indicate their 
quantity and their nature, and we can estimate their composition. 
We furnish to a horse d.iily 4^ lbs. of oats and 15 lbs. of hay ; 
the oats yield 4 per cent., the hay 9 per cent, of ashes ; aud from 
these data we calculate, that the daily excrements of the horse 
must contain 21 ounces of inorganic materials, which have been 
obtained from our fields. The analyses of the ashes of ha> and 
of oats inform us in per centage how much silica, alkalis* a^ij 
phosphates are contained in them.* 

• The ashes of oats contain, according to Saussure — 

In 100 parts. 
Soluble s.'ilt3 vith a.l'r.aiine l)ases - - 16 
Phosphate of lime - - - - - 24 
Silica 60 

The uhee of hay contain, according to Haidlen — 



!79 ON MANURE. 



The nature of the fixed ingredients in the excrements varies 
according lo the food. If we feed a cow on mangel-wurzel, or 
potatoes, without hay or barley straw, its solid excrements will 
not contain silica, but they will contain phosphates of lime and 
magnesia, and the liquid excrements will contain carbonates of 
potash and soda, and also compounds of these bases with inorganic 
acids. If the fodder or food yield, on incineration, ashes contain- 
ing soluble alkaline phosphates (such as bread, meal, all kinds 
of seeds and flesh), we obtain from the animal fed upon these, 
urine in which the alkaline phosphates exist. But if the ashes 
of the food (such as hay, turnips, and potatoes), do not contain 
any soluble phosphate of the alkalies, but only insoluble earthy 
phosphates, then, the urine is free from the alkaline phosphates, 
and the fseces are found to contain the earthy phosphates. The 
urine of men and of animals subsisting upon flesh and grain con- 
tains alkaline phosphates ; while that of animals living wholly 
upon grass is destitute of these salts. The analyses of human 
excrements,* those of birds living upon fish (guano), and of 

In 100 parts 
Phosphate of lime ... - 16 1 

I'erphosphate of lime - - - - 5'0 

Lime 21 

Magnesia ------ 8'6 

Sulphate of soda ----- 1*2 

" potash - - - - 2-2 

Chloride of potassium - - - - 1'3 

Carbonate of soda - - - - 1"1 

" potash - - - - 0-9 

Silica - - - - - - - 60-6 

Loss 0-8 

* According to the analysis of Berzelius, 1000 parts of human urine 
?nntain — 

1000 parts of 1000 parts of 
Urine. the residue. 

Urea 3010 44-39 

Free lactic acid, lactate of ammonia, and ^ 

animal matters not separable from > 1714 25.5S 

them - - - - - - > 

Uric acid ---... l 00 1-49 

Mucus of the bladder - . » - 032 0-48 

Sulphate of potash .... 3-71 5-54 

" soda 3-16 i-12 



EXCREMENTS RESTORE ASHES OF PLANTS. 173 

the excrements of the horse and of the cow (see Aj)pendix)^ 
yield conclusive proof of the nature of the salts contained ir 
them. 

In the solid and liquid excrements of man and of animals, we 

RESTORE TO OUR FIELDS THE ASHES OF THE PLANTS which Served 

to nourish these animals. These ashes consist of certain soluble 
salts and insoluble earths, which a fertile soil must yield, for they 
are indispensable to the growth of cultivated plants. 

It cannot admit of a doubt, that, by introducing these excre- 
ments to the soil, we give to it the power of affording food to a 
new crop, or, in other words, we reinstate the equilibrium which 
had been disturbed. Now that we know that the constituents of 
the food pass over into the urine and excrements of the animal 
fed upon it, we can with great ease determine the dKforent value 
of various kinds of manure. The solid a.\T) liquid excrements 

OF AN ANIMAL ARE OF THE HIGHEST VALUr> AS MANUTIE FOK THOSE 
PLANTS WHICH FURNISHED FOOD TO THE ANIMAL. The dung of 

pigs fed upon peas and potatoes, is in the highest degree adapted 
as a manure for fields growing peas and potatoes. We feed a 

1000 parts of KtOO parts of 

Urine. the residue 

Phosphate of soda ... - 2-94 4-39 

" arrimonia . - - - 1-6.') 2-46 

Chloride of sodiura ... - 4-4.5 6'64 

Muriate of ammonia . - - - I'yO 2'23 

Phosphates of magnesia and lime - - 1*00 1'49 

Silica 0-03 0-05 

Water 933-00 

100-00 

100000 
1000 parts of huntn fxces yielded 150 parts:; 6f asiies, which consisted 
of — (Berzelius) : — 

Phosphate of lime . - - - ) 

" magnesia - - - > 100 

Traces of gypsum . . - - ) 

Sulphate of soda - . - - ) 

" ])otash - - - - > 8 

Phosphate of soda . . - - ) 

Carbonate of soda ... - 8 

Silica 16 

Carbonaceous residue and loss - - - 18 

150 



174 ON MANURE. 



cow upon hay and turnips, and we obtain a manure containing 
all the mineral constituents of grass and of turnips ; this manure 
ought to be preferred, as being more suitable for turnips than 
that procured from any other source. The dung of pigeons con- 
tains the mineral ingredient of the cereal grains ; that of the 
rabbit, the constituents of culinary vegetables ; the liquid and 
solid excrements of man contain in very great quantity the 
mineral substances of all seeds. 

According to the above view, a knowledge of the constituents 
of the ashes of food and of fodder, gives us an exact indication 
of the ingredients of the soil contained in the liquid and solid ex- 
crements of men and of animals. 

If we know the quantity of the food, and the composition of its 
ashes, we know also with certainty how much soluble salts will 
be contained in the urine, and how much of the insoluble salts 
will exist in the faeces. It would, therefore, be superfluous and 
useless to state here a greater number of analyses of excrements, 
because these analyses must differ from each other, quite as 
much as the variation in composition of the ashes of the food on 
which the animal was fed. 

Conunon stable manure is a mixture of stolid excrements with 
urine, which gradually enters into putrefaction in the dunghill. 
In consequence of the putrefaction of the urine, all the urea con- 
tained in it is converted into volatile carbonate of ammonia. A, 
large portion of the organic ingredients of the manure enter into 
dpcty and assume a gaseous condition, by the action of the air, 
with the continued evolution of heat. The weight of these 
ingredients diminishes, while the relative proportion of the fixed 
mineral substances increases. If all the decaying matters 
entered into union with oxygen, the result of course would be, 
that those not susceptible of decay, or, in other words, the ashes, 
would alone remain behind. The following analysis will illus. 
trate the meaning of this remark : — 

100 })arts t'resh Cow-dung — 

W;itcr S5-900 

Combustible substances - 12'352 ) i , ,r,A 
Ashes ... - 1-74S5 ^"^ ^^^ 



100000 



MANURE LOSES ORGANIC MATTER BY AGE. \T. 



100 parts Stable Manure i year old.* 

Water 79-3 

Coinbustible substances - 14'04 ) „„ _ 
Ashes 6 66 5 '*"'' 

100.0 

Now that we knov/ that the proportion of the mineral food of 
plants increases ■vviih the age of the dung, that old dung may 
contain 4 to 6 times more of it than fresh dung, an explanation is 
furnished of the relatively greater action of the former, and of 
the preference accorded to it by farmers of experience. 

It has been mentioned in the preceding part of the chapter, 
that animal excrements may be replaced in agriculture, by other 
materials containing their constituents. Now, as the principal 
action of the former depends upon their amount of mineral food 
so necessary for the growth of cultivated plants, it follows, that 
we might manure with the mineral food of wild plants, or in 
other words, with their ashes ; for these plants are governed 
by the same laws, in their nutrition and growth, as cultivated 
plants themselves. Thus, these ashes might be substituted for 
animal excrements ; and if a proper selection were made of them, 
we might again furnish our fields with all the constituents 
removed from them by crops of cultivated plants. The vast im- 
portance of ashes as a manure is recognised by many farmers. 
In the vicinity of Marburg, and in the Wetterau, such a high 
value is attached to this costly material, as a manure, that the 
farmers do not object to send for t to a distance of 18 or 24 miles. 
The importance of this manure will be more obvious, when it is 
considered, that wood-ashes lixiviated with cold water contain 
silicate of potash, in exactly the same proportion as straw 
(10 Si O3, + KO) ; and that, in addition to this salt, it contains 
considerable quantities of phosphates. 

Different kinds of wood-ashes ])ossess very unequal value as 
manure. Thus, the asi.e^ of the oak are of the smallest, those 
of the beech of r;c greatest value. Wood-ashes from oak contain 
4 to 5 per cent, of p':'.csphatfs : those from the beech contain the 
fifth part of their weight of these salts. The quantity of phos- 

• Annales de Cliimie et de Pliysique, iii. Serie, 237. 



176 ON MANURE. 



phales in the ashe? of firs and pines amounts to from 9 to 15 per 
cent. : the ashes of the poplar contain 16| per cent., and those 
of the hazel-nut tree 12 per cent.* 

With every hundred pounds of lixiviated ashes of the beech, 
we furnish to the soil as much phosphates as are contained in 
460 lbs. of fresh human excrements. 

According to the analysis of Saussure, 100 parts of the ashes 
of grains of wheat contain 32 parts soluble and 44-5 parts inso- 
luble, or altogether 76'5 parts of soluble and insoluble phosphates. 
The ashes of wheat-straw contain in all 11*5 per cent, of phos- 
phates. Thus with every 100 lbs. of the ashes of beech, we 
furnish to the field phosphoric acid sufficient for the production 
of 4000 lbs. of straw (calculating its ashes at 4 per cent., accord- 
ing to Saussure), or for 2000 lbs. of the grains of wheat (calcu- 
lating their ashes at 1-3 per cent. — Saussure). 

The dry fruit of the horse-chestnut (jEscuIus Jiippocastanum) 
yields 34 per cent, of ashes, possessing a similar composition to 
the ashes of maize, and of the grain of certain kinds of wheat. f 

The importance of manuring with bones must be obvious to 
all. The bones of man, and of animals in general, have their 
origin from apatite (phosphate of lime), which is never absent 
from fertile land. The bone earth passes from the soil into hay, 
straw, and other kinds of food, which are afterwards consumed 
by animals. Now, when we consider that bones contain 55 per 
cent, of the phosphates of lime and magnesia (Berzelius), and il 
we assume that hay contains the same quantity of these salts as 

* Ashes of pines from Norway contain the minimum of phosphates— 
viz. 09 per cent. — Berthier. 

t Ashes of the fruit of the horse-chestnut [Savssuhe]: 

Potash 51 

Alkaline phosphates - . - - 2S 

Chloride of potasnium and sulphate of ) „ 

potash - - - - - ) 
Earthy phosphates - . . . 12 

Silica - 0-5 

Metallic oxides ... - - 0-25 
L0S8 - 5-25 

10000 



BONE MANURE. 177 



wheat-straw, then it follows that 8 lbs. of bones contain as much 
phosphate of lime as 1000 lbs. of hay or of wheat-straw, and 20 
lbs. as much phosphoric acid as 1000 lbs. of the grain of wheat 
or of oats. These numbers are not absolutely correct, but they 
give a very fair approximation of the quantity of phosphates 
yielded annually by a soil to these plants. By manuring an acre 
of land with 60 lbs. of fresh bones, we furnish sufficient manure 
to supply three crops (mangel-wurzel, wheat, and rye) with 
phosphates. But the form in which they are restored to a soil 
does not appear to be a matter of indifference. For the more 
finely the bones are reduced to powder, and the more intimately 
they are mixed with the soil, the more easily are they assimi- 
lated. The most easy and practical method of effecting their 
division is to pour over the bones, in a state of fine powder, half 
their weight of sulphuric acid diluted with three or four parts of 
water, and after they have been digested for some time, to add 
about one hundred parts of water, and to sprinkle this acid mix- 
ture (phosphates of lime and magnesia) before the plough. In a 
few seconds, the free acids unite with the bases contained in the 
earth, and a neutral salt is formed in a state of very fine division. 
Experiments instituted on a soil formed from grauwacke, for the 
purpose of ascertaining the action of the manure thus prepared, 
have distinctly shown that neither corn nor kitchen-garden plants 
suffer injurious effects in consequence ; but that, on the contrary, 
they thrive with much more vigor.* 

In the manufactories of glue, many hundred tons of a solution 
of phosphates in muriatic acid are yearly thrown away as be 
ing useless. It would be important to ascertain how far this 
solution might be substituted for bones. The free acid would 

* Very favorable results have been obtained by treating seeds in the fol 
lowing manner: — The seeds about to be sown were steeped in the water 
from a dunghill, and while still wet, were strewed with a mixture of 20 
parts of fine bone-dust and 1 part of burnt gypsum, in such a manner that 
each grain was covered with a thin layer of the powder; by sprinkling 
them with water and repeating this treatment with the mixture, tJie coat- 
ing can be increased. The seeds were allowed to dry in the air, and were 
then sown in the usual way. On tlie large scale this mode of dunginj 
owing to its being rather troublesome, might not answer the purpose ■<! 
well as a heavy manuring with bones and gypsum. 
9* 



17S ON MANURE 



combine with the alkalies in the soil, especially with lime, and a 
soluble salt would thus he. pi'oduced, which is Icnown to possess u 
favorable action on the growth of plants. This salt (muriate of 
lime, or chloride of calcium) is one of those compounds which 
attract water from the atmosphere with great avidity, and retain 
it when absorbed ; and being present in the soil, it would decom- 
pose the carbonate of ammonia existing in rain-water, with the 
formation of sal-ammoniac and carbonate of lime. A solution 
of bones in muriatic acid placed on land in autumn or in winter, 
would therefore not only restore a necessary constituent of the 
soil, but would also give to it the power of retaining all the am- 
monia falling upon it in the rain for a period of six months. 

The ashes of brown coal and of peat contain frequently silicate 
of potash, so that these might furnish to the straw of the cereals 
one of its principal constituents ; these ashes contain also 
phosphates. 

It is of much importance to the agriculturist, that he should 
not deceive himself respecting the causes which give the peculiar 
action to the substances just mentioned. It is known that they 
possess a favorable action on vegetation ; and it is likewise cer- 
tain, that the cause of this is their containing a body, which, inde- 
pendently of the influence exerted by its physical properties of 
porosity and capability of attracting and retaining moisture, as- 
sists also in maintaining the vital processes of plants. But if the 
subject be treated as an unfathomable mystery, the nature of 
their influence will never be known. 

In medicine, for many centuries, the mode of action of all reme- 
dies was supposed to be concealed by the mystic veil of Isis ; 
but now these secrets have been explained in a very simple man- 
ner. An unpoetical hand has pointed out the cause of the won- 
derful and apparently inexplicable healing virtues of the springs 
in Savoy, by which the inhabitants cured their goitre : the water 
was found to contain small quantities of iodine. In burnt sponges 
used for the same purpose, the same clement was also detected. 
Tiie extraordinary efiicacy of Peruvian banc was found to depend 
on a small quantity of a crystalline body existing in it, viz. 
quinine ; and the causes of the various effects of opium were 
detected in as manv different ingredients of that drug. 



CAUSES OF ACTION SHOULD BE ASCERTAINED. i ? .• 

Now all such actions depend on a definite cause, oy ascertain, 
ing which, we place the actions themselves at our command. 

It must be admitted as a principle of agriculture, that those 
substances which have been removed from a soil must be com- 
pletely restored to it ; but whether this restoration be effected bv 
means of excrements, ashes, or bones, is in a great measure d 
matter of indifference. A time will come, when plants growing 
upon a field will be supplied with their appropriate manures pre- 
pared in chemical manufactories — when a plant will receive only 
such substances as actually serve it for food, just as at present a 
few grains of quinine are given to a patient afflicted with fever 
instead of the ounce of wood which he was formerly compelled 
to swallow in addition. 

There are some plants which require humus (as a source of 
carbonic acid), without re-producing it in any appreciable quantity ; 
whilst others can do without it altogether, and actually enrich a 
soil deficient in it. Hence a rational system of agriculture would 
employ all the humus at command for the supply of the former 
and not expend any of it for the latter ; but would in fact maka 
use of them for supplying the others with humus. 

We may furnish a plant with carbonic acid, an4 with all the 
materials which it may require ; we may supply it with humus 
in the most abundant quantity ; but it will not attain complete 
development, unless nitrogen is also afforded to it ; a herb will 
be formed, but no grain ; even sugar and starch may be produced, 
but no gluten. 

But, on the other hand, the supply of nitrogen, in the form of 
ammonia, will not suffice for the purposes of agriculture. Al 
though ammonia is of the utmost importance for the vigorous 
growth of plants, it is not in itself sufficient for the production of 
vegetable casein, fibrin, or albumen. These substances are not 
known in a free state ; for they are always accompanied by alka- 
lies, sulphates, and phosphates. We must therefore assume, that 
without their co-operation, ammonia could not exercise the slight- 
est influence on the growth and formation of the seeds ; that, in 
such a case, it is a matter of perfect indifference whether am- 
monia is conveyed to them or not ; for it will not assist in the 
formation of the constituents of the blood, unless tlie other condi- 



ISO JN MANURE. 



tions necessary for their production he present at the same 
time. 

All these conditi ns are united in liquid and solid excrements; 
none of them are absent. In these are present, not only ammo- 
nia, but also alKaliss, phosphates, and sulphates, in the relativfl 
pre -rtion in which they exist in our cultivated plants. 

The powerful action 'f urine depends, therefore, not only on 
Its compounds of nitrogen ; for the phosphates and sulphates ac- 
companying these take a v'.ecided part in the action. 

Urine, in the state in which it is used as manure, does not con- 
tain urea, as this substance has been converted into carbonate of 
ammonia during putrefaction. In dung reservoirs, well con- 
structed and protected from evaporation, the carbonate of ammo- 
ma is retained in solution. When the putrefied urine is spread 
over the land, part of its carbonate of ammonia evaporates along 
with the water, while another portion is absorbed by the soil, par- 
icularly if it be clayey and ferruginous land ; but, in general, 
only the phosphate and muriate of ammonia remain in the ground. 
The amount of the latter alone enables the soil to exercise a 
direct influence on the plants during the progress of their growth ; 
and as they are not volatile, not a particle of them escapes being 
absorbed by the roots. 

The existence of carbonate of ammonia in putrefied urine long 
since suggested the manufacture of sal-ammoniac from this ma- 
terial. When the latter salt possessed a high price, this manu- 
facture was carried on by the farmer himself. For this purpose 
the liquid obtained from dunghills was placed in vessels of iron 
and subjected to distillation ; the product of this distillation was 
then converted into muriate of ammonia by the ordinary methods 
(Demachy). 

The carbonate of ammonia formed . y the putrefaction of urine 
can be fixeJ, or be deprived of its volatility, in many ways. 
When a field is strewed with gypsum, and then with putrefied 
urine, or with the drainings of dunghills, all the carbonate of 
ammonia is converted into the sulpliatc, which remains in the 
soil. 

But there are still simpler means of effecting this purpose : 
gypsnir), cliloiide of calcium, sulphuric or muriatic acid, and 



CARBONATE OF AMMONIA IN L-?'N.^ 181 

superphosphate of lime, are substances of a very low price ; and 
if they were added to urine until the latter lost its alkalinity, the 
ammonia would be converted into salts, which would have ::c 
further tendency to volatilize. 

When a basin, filled with concentrated muriatic acid, is placed 
in a common necessary, so that its surface is in free communica- 
tion with the vapors issuing from below, it becomes filled after a 
few days with crystals of muriate of ammonia. The ammonia, 
the presence of which the organs of smell amply testify, combines 
with the muriatic acid and loses entirely its volatility, and thick 
clouds or fumes of the salt newly-formed hang over the basin. In 
stables, the same may be seen. The ammonia escaping in thi? 
manner is not only lost, as far as our vegetation is concerned, but 
it works also a slow, though not less certain, destruction of the 
walls of the building. For, when in contact with the lime of the 
mortar, it is converted into nitric acid, which dissolves gradually 
the lime. The injury thus done to a building by the forrnaticr 
of soluble nitrates, has received (in Germany) a special name ■ 
salpeterfrass (production of soluble nitrate of lime). 

The ammonia emitted from stables and necessaries is alway-- 
in combination with carbonic acid. Carbonate of ammonia and 
sulphate of lime (gypsum) cannot be brought together at common 
temperatures, without mutual decomposition. The ammcnia 
enters into combination with the sulphuric acid, and the carbanio 
acid with the lime, forming compounds destitute of volatility, aiid 
consequently of smell. Now, if we strew the floors of our stables. 
from time to time, with common gypsum, they Avill lose all their 
offensive smell, and none of the ammonia can be lost, but will be 
retained in a condition serviceable as manure (Mohr). 

With the exception of urea, uric acid contains more nitroger; 
than any other substance generated by the living organism ; it ig 
soluble in water, and can be thus absorbed by the roots of plants, 
and its nitrogen will be assimilated in the form of ammonia from 
the oxalate, hydrocyanate, or carbonate of ammonia. It would 
be extremely interesting to study the transformations which uric 
acid suffei's in a living plant. For the purpose of experiment, 
the plant should be made to grow in charcoal powder previously 
heated to redness, and then mixed with pure uric acid. The ex. 



tS2 ON MANURE. 



amination cf the juioe of the plant, or of the component parts of 
the seed or fruit, would be an easy means of detecting the 
differences. 

In respect to the quantity of nitrogen contained in excrements, 
100 parts of the urine of a healthy man are equal to 1300 parts 
t)f the fresh dung of a horse, according to the analysis of Macaire 
and Marcet, and to 600 parts of the fresh dung of a cow. 
The powerful effects of urine as a manure are well known in 
Flanders, and they are considered invaluable by the Chinese, who 
ire the oldest agricultural people we know. Indeed, so much 

alue IS attached to the influence of human excrements by these 
oeople, that laws of the state forbid that any of these excrements 
should be thrown away, and reservoirs are placed in every house, 

n which they are collected with the greatest care. No other 
Kind of manure is used for their corn-fields. 

On the assumption, that the liquid and solid excrements of man 

amount, on an average, to only 1| lb. daily (-f- lb. of urine and 
^ lb. fiieces), and that both taken together contain 3 per cent, of 
nitrogen, then, in one year, they will amount to 547 lbs., con- 
laining 16-41 lbs. of nitrogen, a quantity sufficient to yield the 
nitrogen of 800 lbs. of wheat, rye, oats, or of 900 lbs. of barley. 

(BOUSSINGAULT.) 

This IS much more than it is necessary to add to an acre of 
'.and, in order to obtain, with the assistance of the nitrogen ab-. 
sorbed from +he atmosphere, the richest crops every year. By 
adopting a system of rotation of crops, every town and farm might' 
thus supply itself with the manure, which, besides containing 
the most nitrogen, contains also the most phosphates. By using, 
at the same time, bones and the lixiviated ashes of wood, animal 
excrements might be completely dispensed with on many kinds 
of soil . 

When human excrements are treated in a proper manner, so aa 
to remove this moisture, without permitting the escape of am- 
monia, they may be put into such a form as will allow them to be 
ransported even to great distances. 

This is already attempted in many towns, and the preparation 
of night-soil for transportation constitutes not an unimportant 
branch of industry. 



NITROGEN IN EXCREMENTS. 183 



In Paris, for example, the excrements are preserved in the 
houses in open casks, from wiiich they are collected and placed 
in deep pits at Montfau^on, but they are not sold until they have 
attained a certain degree of dryness, by evaporation in the air. 
But whilst lying in the receptacles appropriated for them in the 
houses, all their urea is converted for the most part into carbonate 
of ammonia : the vegetable matter contained in them putrefies, 
all the sulphates are decomposed, and the sulphur forms sul- 
phuretted hydrogen (volatile hydrosulphate of ammonia). The 
mass, when dried by exposure to the air, has lost the greatest part 
of its nitrogen along with its water, and the residue, besides phos- 
phate of ammonia, consists for the most part of phosphate of lime 
and magnesia, together with fatty matters. This manure is sold 
in France under the name of Foudrelle, and is very highly esti- 
mated, on account of its powerful action. Tliis action cannot 
depend on the ammonia originally contained in it, because the 
greale.st part has escaped daring the desiccation. According to 
the analyses of Jaquemars, the Parisian poudrctte does not con- 
tain more than 1'8 per cent, of ammonia. 

In other manufactories of manure, the night-soil, whilet still 
soft, is mixed with the ashes of wood, or with earth, &:c., con- 
taining a large quantity of caustic lime, and this causes a com- 
plete expulsion of all the ammonia of the excrements, depriving 
them in consequence of all smell. The efficacy of this manure 
cannot, therefore, depend upon its nitrogen. 

It is evident that, if we place the solid or liquid excrements of 
man, or the liquid excrements of animals on our land, in equal 
proportion to the quantity of nitrogen removed from it in the 
form of plants, the sum of this element in the soil must increase 
every year ; for to the quantity which we thus supply, another 
portion is added from the atmosphere. There is no propei loss 
of nitrogen to plants, for even the small quantity of this element 
which man carries with him to the grave is not finally lost to 
vegetation, for it escapes into the earth, and into the atmosphere, 
as ammonia, during the decay and putrefaction of the body. 

A high degree of culture requires an increased supply of ma. 
nure. With the abundance of the manure the produce in corn ana 
cattle will augment, but must diminish with its deficiency. 



184 ON MANURE. 



The substances applicable as manure ought to be arranged 
according to the products desired. The alkalies are peculiarly 
necessary for the production of vegetable constiiuents destitute 
of nitrogen, such as sugar, starch, pectin, and gum ; phosphates 
are peculiarly valuable for the formation of the constituents of 
the blood. A field richlv treated with animal manui^e, and 
thei'efore with phosphates, produces a barley which is rejected 
by the brewer of beer, because it is too rich in the constituents 
of the blood, and proportionally poor in starch. Hence, the 
very ingredient which is of the highest value to the feeders of 
stock, is held in low estimation by the brewer ; because the 
object of the first is to produce flesh, the object of the latter is 
the fabrication of alcohol. 

Fresh bones, v/ool, hair, rags, hooi's, and horn, are manures 
containing nitrogen as well as phosphates, and are consequently 
fit to aid the process of vegetable life. 

One hundred parts of dry bones contain from 32 to 33 per 
cent, of dry gelatine ; now, supposing this to contain the same 
quantity of nitrogen as aninaal glue — viz. 5-28 per cent., then 
100 parts of bones must be considered as equivalent to 250 parts 
of human urine. 

Bones may be preserved for thousands of years, in dry, or 
even in moist soils, provided the access of air is prevented ; as is 
exemplified by the bones of antediluvian animals found in loam 
or gypsum, the interior parts being protected by the exterior 
from the action of water. But they become warm when reduced 
to a fine powder, and moistened bones generate heat and enter 
into putrefaction ; the gelatine is decomposed, and its nitrogen 
is converted into carbonate of ammonia and other ammoniacal 
salts, which are retained in a great measure by the powder 
itself.* 

Charcoal, in a state of powder, must be considered as a very 
Dowerful means of promoting the growth of plants on heavy 
soils, and particularly on such as consist of argillaceous eartli. 

Ingenhouss proposed dilute sulphuric acid as a means of in- 

• Bones burnt till quite white, and recently heated to redness, absorb 
7'5 times their volume of pure ammoniacal gas. 



BONE MANURE. is5 



creasing the fertility of a soil. Now, when this acid is sprinkled 
on calcareous soils, gypsum (sulphate of lime) is immediately 
formed, which, of course, prevents the necessity of manuring the 
ground with this material. 100 parts of concentrated sulphuric 
acid diluted with from 800 to 1000 parts of water, are equiva- 
lent to 176 parts of gypsum. 

Many kinds of ashes, of peat, and most varieties of coal 
ashes, contain an abundant quantity of gypsum, by which they 
exercise a very favorable fhfluence on certain soils. 







Ashes of peat 


Ashes of peat 




from Fichtelgebirge. 


from Bassy (0ep. de la Morn*) 






FlKENTSCHKR 


Bkkthiek. 


Silica - 


. 


3G-5> 




Alumina 


- 


17-3 S - 


- 22-5 


Peroxide of iron 


- 


33-0) 




Carbonate of lime 


. 


20) 

3-5 5 - - 


- 51-5 


Magnesia 


- 


Gypsum - 


- 


4-5 


. 26-0 


Chloride of calcium 


0-5 




Carbonaceous residue 


: 2-7 





ISe RETROSPECT. 



CHAPTER XIII. 

Retrospective View of the Preceding Theories. 

The knowledge of the processes of nutrition, in the case of the 
culture of meadow and of forest land, indicates that the atmo- 
sphere contains an inexhaustible quantity of carbonic acid. 

On equal surfaces of wood or of meadow land, in which exist 
the constituents of the soil indispensable to vegetation, we obtain 
crops without the application of carbonaceous manures ; and 
these crops contain, in the form of wood and hay, a quantity of 
carbon equal to, or, in many cases, greater than that produced 
by cultivated land in the form of straw, corn, and roots. 

It is obvious that the cultivated land must have presented to it 
as much carbonic acid as is furnished to an equal surface of 
wood or of meadow land ; that the carbon of this carbonic acid 
becomes assimilated, or is capable of assimilation, if the con- 
ditions exist for its reception and conversion into a constituent 
of plants. 

However great may be the supply of food in a soil, it will be 
sterile for most plants, if water be deficient. At certain seasons 
of the year rain fructifies our fields; seeds neither germinate 
nor grow without a certain quantity of moisture. 

The action of rain is much more striking and wonderful to the 
superficial observer than that of manure. For weeks and 
months, the influence which it exerts on the crops is appreciable, 
and yet very small quantities of carbonic acid and ammonia are 
introduced to the soil by mean^ of rain. 

Water plays, doubtless, a decided part in the growth of plants, 
by virtue of its elements ; but, at the same time, it is a mediating 
member of all organic life. Plants receive from the soil, by the 
aid of water, the alkalies, alkaline earths and phosphates neces- 
sary to the formation of thsir organs. If these substances, 



CARBONIC ACID FURNISHED BY HUMUS. 187 



ivhich are necessary for the passage of atmospheric food into the 
organism of the plant, be deficient, its growth must be impeded. 
Its proper growth, in dry seasons, stands in exact relation to the 
quantity of the substances taken up from the soil during the first 
period of its development. But on a soil poor in mineral food, 
cultivated plants do not flourish, however abundantly water may 
be supplied to them. 

The crop of a meadow, or of an equal surface of wood-land, is 
quite independent of carbonaceous manures, as far as regards 
its carbon ; it is dependent on the presence of certain ingredients 
of the soil destitute of carbon, and also on the conditions which 
enable these to enter into the plants. No\v, we are able to in- 
crease the crop of carbon on our cultivated land, by the use of 
burnt lime, ashes, or marl, — by substances, therefore, which are 
entirely free from carbon. This well-ascertained fact indicates 
that we furnish to the field, in these substances, certain constitu- 
ents, which enable the cultivated plants to increase in mass, and 
consequently in carbon — a power which they possessed formerly 
only in a small degree. 

After these considerations, it cannot be denied that the sterility 
of a field, or its poverty of produce in carbon, does not arise 
from a deficiency of carbonic acid, or of humus ; for we have 
seen that this produce can be increased, to a certain extent, by 
the supply of matters destitute of carbon. But the very same 
source which supplies the meadow and woodland with carbon, 
namely the atmosphere, can yield that element to cultivated 
plants. It therefore becomes especially necessary in agriculture 
to employ the best, and most convenient means, of enabling the 
carbon of the atmosphere (carbonic acid) to pass over into the 
plants growing on our fields. The art of agriculture, in the 
mineral food which it supplies, furnishes to plants the means of 
appropriating their carbon from sources offering an inexhaustible 
provision. But when these constituents of the soil are wanting, 
the most abundant supply of carbonic acid, or of decaying vege- 
table matter, cannot increase the crops on the field. 

The quantity of carbonic acid that can pass from the air into 
plants, is limited, in a given time, by the quantity of carbonic 
ac'd entering into contact with the organs destined for its absorp- 



188 RETROSPECT 



tion. Now, the passage of carbonic acid from the air into the 
organism of tlie plant is effected by means of the leaves ; but 
the absorption of carbonic acid cannot take place without the 
contact of its particles with the surface of the leaf, or of a part 
of the plant capable of absorbing it. Hence, in a given tinii 
the quantity of carbonic acid absorbed must stand in exact pro- 
portion to the surface of the leaves, and to the amount of it exist- 
ing in the air. 

Two plants of the same kind, with equal surfaces of leaves 
(i. e. surfaces of absorption), will take, during the same time, and 
under like conditions, the same amount of carbon. And if the 
air contains double the quantity of carbonic acid that it does at 
another time, the plants, under like condhions, will absorb double 
the quantity of carbon.* A plant with only half the surfaces 
of the leaves of another plant will absorb quite as much carbon 
as the latter, if the air supplied to the former contains twice the 
amount of carbonic acid. 

These considerations point out to us the cause of the favorable 
action exerted on cultivated plants by humus, and by all decaying 
organic substances. 

Young plants, when dependent on the air alone, can only 
increase their amount of carbon according to their absorbing- 
surfaces. But it is obvious, if their roots receive, by means of 
humus, three times the amount ol carbonic acid absorbed bv 
their leaves in the same time, their increase in weight will be 
fourfold, on the assumption of the existence of all the conditions 
for the assimilation of the carbon. Hence, four times the quan- 
tity of stems, leaves, and buds, must be formed ; and, by the 
increased surface thus obtained, the plants will receive in the 
same degree an increased power of absorbing food from the air ; 
and this power remains in activity long after the supply of carbon 
to the roots has ceased. 

But the use of humus as a source of carbonic acid, in arable 
land, is not only to increase the amount of carbon in the plant ; 

* Boussingault remarked that leaves of a vine inclosed in a globe re- 
moved comirletely from the air all the carbonic acid contained in it, how 
ever rapidly the stream of air was made to pass, (Dumas: Lectures, 
p. 23.) 



UNEQUAL PRODUCTION OF CONSTITUENTS. 1S« 

for, by the increased size attained by the plant in a gi^'en time, 
there is also given, in fact, space for the reception of the consti- 
tuents of the soil necessary for the formation of new leaves and 
twigs. 

From the surface of young plants a constant evaporation of 
water takes place, the amount of which is in proportion to the 
temperature and surface. The numerous fibres of the roots 
supply the water which is evaporated, just as if they were so 
many pumps ; so that, as long as the soil continues moist, the 
plants receive, by means of water, the necessary constituents of 
the soil. A plant with double the surface of another plant must 
evaporate twice the quantity of water that the latter does. The 
water thus absorbed is expelled again in vapor, but the salts and 
constituents of the soil introduced to the plant by its agency, 
still remain there. A plant with twice the surface of leaves of 
another plant, but with the same quantity of water in proportion 
to its size, still receives from the same soil a greater quantity 
of ingredients, in proportion to its water, than the latter plant 
receives. 

The growth of the latter soon reaches a termination when the 
further supply ceases, while the former continues to grow, be- 
cause it contains a larger quantity of the substances necessary 
for the assimilation of atmospheric food. But m both plants the 
number and size of the seeds will altogether depend upon the 
amount of the mineral ingredients of the seed existing in the 
plants ; the plants containing or receiving from the soil a greater 
amount of alkaline and earthy phosphates than other plants obtain 
in the same time, will also produce a greater number of seeds 
than the latter. 

Thus it is that, in a hot summer, when the supply of the con- 
stituents of the soil is cut off by rain, the height and strength of 
the plants, and the development of the seed, stand in exact pro- 
portion to the quantity of the constituents of the soil taken up 
during their former period of growth. 

The produce of a field in corn and in straw varies very con- 
siderably in different years. In one year we may obtain the 
same weight of corn of similar composition to that obtained in 
•nether year, but the crop of straw may be considerably greater; 



190 RETROSPECT. 



or the reverse rnay take place, and the crops of" straw (of carbon) 
may be equal, while the corn may amount to double the quantity 
But when we obtain twice the quantity of" corn from the same 
surface, we must have also a corresponding increase of the con- 
stituents of the soil in the corn ; or, when we obtain twice the 
quantity of straw, there must be twice the amount of the ingre- 
dients of the soil in the straw. In one year the wheat may be 
3 feet in height, and yield 1200 lbs. of seed per acre, while, in 
another year, it may grow one foot higher, and yet yield only 
800 lbs. 

An unequal crop indicates, under all circumstances, an une- 
qual proportion of the constituents of the soil taken up for the 
formation of the corn and of the straw. Straw contains and 
requires phosphates, as well as corn, but in much smaller pro- 
portion. 

In a wet spring, when the supply of these salts is not so great 
as that of alkidies, of silica, and of sulphates, the crop of seeds 
becomes diini.'iis'Dod ; because a certain quantity of the phos- 
phates, which Would otherwise be employed in the formation of 
the seeds, is now used for the production of the stem and leaves; 
the constituents of the seeds cannot be perfected without an 
abundant supply of phosphates. By depriving a plant of these 
salts, we could produce artificially the state ia which they attain 
a height of three feet, and blossom without ihe production of 
seeds. The crop of corn growing on a soil rich in the consti- 
tuents of straw (a fat soil), is often less in a wet spring than upon 
a soil poor in these ingredients (a thin soil), because the supply 
of mineral food on the latter is greater in the same time, and is 
in better proportion for the growth of all the constituents of plants 
than in the former case. 

On the supposition that all the conditions necessary to our cul- 
tivated plants, for the assimilation of food from the atmosphere, 
existed in the most favorable form, yet the action of humus would 
be useful in effecting a more rapid growth of the plants, and 
thus GAINING TIME, in all cases, the crop of carbon is increased 
by means of humus ; and if the conditions be absent tor the con- 
version of this element into other constituents, it a9a"'*>'^ the 



AMOUNT OF NITROGEN IN DIFFERENT CROPS. 1-Ji 

form of starch, gum, and of sugar, that is, of substances rlestv 
lute of mineral ingredients. 

Every moment of time is of value in the practice of farming , 
and, in this respect, humus is of especial importance in kitchen 
gardening. 

Our corn plants and edible roots find in our fields, in the form 
of the remains of a past vegetation, sufficient vegetable matter tc 
correspond to the mineral food existing in the soil, and, therefore, 
with sufficient carbonic acid to produce a quick growth during 
spring. Any further supply of carbonic acid would be wholly 
useless, unless it were accompanied by a corresponding increase 
of the mineral constituents adapted to form parts of the plant. 
Upon a Hessian acre of good meadow land we obtain 2500 lbs. of 
hay, according to the opinion of experienced farmers. Meadows 
yield this crop, without any supply of organic matters, 'r with- 
out any manures containing nitroger or carbon. By proper irri- 
gation, and by treatment with ashes and gypsum, the crop can 
be increased to double the amount. Let us assume, however, 
that the 2500 lbs. of hay form the maximum crop ; still, it is 
certain that all the carbon and nitrogen of the plants constituting 
it must have been obtained from the air. 

According to Boussingault, hay, dried at the temperature of 
boiling water, contains 45*8 per cent, of carbon (a result agree- 
ing with analyses made in this laboratory), and 1*5 per cent, ol 
nitrogen; hay dried in air still retains 14 percent, of water, 
which escapes at the heat of boiling water. 

2500 lbs. of hay, dried in air, correspond to 2150 lbs. of hay 
dried at the temperature of boiling water. With the 984 lbs. of 
carbon contained in the crop of 2150 lbs. of hay, we have also 
removed from the acre of meadow-land 32*2 lbs. of nitrogen. 
If we assume that this nitrogen has entered the plant in the form 
of ammonia, it is obvious that for every 3640 lbs. of carbonic 
acid (calculated at 27 per cent, of carbon) the air contains 39-1 
lbs. ammonia (taken at 82 per cent, of nitrogen) ; or that, for 
every 1000 lbs. of carbonic acid, the air contains 10-,^o- lbs., am- 
monia — a quantity corresponding to about -yo oTTo" o^ ^^^^ weight 
of the air, or of ttVo'o o^ ^^^ volume. 

Thus fcr every 100 parts of carbonic acid absorbed by tho 



182 RETROSPECT 



surface of the leaves of the meadow plants, there must also be 
absorbed from the air above one part of ammonia. When we 
calculate how much nitrogen different plants obtain from equal 
surfaces of land, basing our calculations r^i known analyses, the 
following results are obtained : 

1000 lbs. of carbon remove in nitrogen— 

From meadow land, in hay - - 32'7 

" arable land, in wheat - - - 21 "5 

" " oats - - . 22-3 

rye - - - 15-2 

" " potatoes ... 34-1 

" " mangel-wurzel - - 39"l 

" " clover - - - 44 

'.' " peas - - - 62 

These facts lead to certain conclusions of high importance to 
agriculture. We observe, in fact, that the proportion of nitro- 
gen absorbed, relatively to that of carbon, stands in a fixed rela- 
tion to the surface of the leaves. 

1. Plants containing nearly all their nitrogen concen- 
trated IN their seeds, such as the cereals, contain alto- 
gether LESS NITROGEN THAN THE LEGUMINOUS PLANTS, TEAS AND 

clover. 

2. The crop of nitrogen from a meadow to which no 
azotized manure has been given, is much greater than that 
from a manured field of wheat. 

3. The crop of nitrogen in clover or in peas is much 
greater than that of a highly-manured field of potatoes 
or of turnips. 

Boussingault obtained in five years, from his farm in Bechel- 
bronn, Alsace, in the form of potatoes, wheat, clover, turnips, and 
oats, 8383 carbon, and 250-7 nitrogen ; in the succeeding five 
years,* 8192 carbon, 284-2 nitrogen ; in a third rotation of six 
years,! 10949 carbon, 353-6 nitrogen ; or, in sixteen years. 
27424 carbon, and 858-5 nitrogen ; or altogether, in the pro- 
portion OF 1000 CARBON to 31-3 NITROGEN. 

• Beet, wheat, clover, wheat, late turnips, oats, rye. 
i Potatoes, wheat, clover, wheat, late turnips, peas, rye 



INORGANIC MANURE. 193 

A most remarkable and important result follows from this ex- 
periment — that when potatoes, wheat, turnips, peas, and clover 
(fotash, lime, and silica plants), are cultivated successively on 
the same field, although this field had been thrice manured in the 
course of sixteen years, the same relation of nitrogen to a given 
quantity of carbon is obtained, as in the case of a meadow which 
had received no manure. 

Carbon. Nitrogen. 
Upon an acre of meadow land there is cropped of silica, > „„ . o-t-.t 

lime, and potash plants, taken together - - > 
On an acre of arable land, on a sixteen years' average, of ) „,_ op.q- 

silica, lime, and potash plants - - - ^ 

When we take into consideration the amount of carbon and 
nitrogen in. the leaves of the beet and potatoe (for the leaves 
were not calculated in the produce of the arable land), then it 
follows that, notwithstanding all the supply of carbon and of ni- 
trogen furnished in the manure, the arable land has not produced 
more of these elements than an equal surface of meadow land, 
WHICH RECEIVED ONLY MINERAL FOOB (constituents of the soil). 

Then, on what depends the peculiar action of manures, 
and of the liquid and solid excrements of animals ? 

This question is susceptible of a simple solution. These 
manures have a very decided action on our ai'able land, from 
which for centuries we have removed, in the form of cattle and 
of corn, a certain quantity of constituents of the soil which have 
not been restored. 

If no manure had been applied to the land during the sixteen 
years of the above experiment, the crop would have mounted to 
only a half or third part of the carbon and nitrogen. 

The liquid and solid excrements used as manure enabled this 
surface of arable land to produce as much as the meadow land. 

But notwithstanding the amount of manure supplied, the field 
was no richer in the mineral food of plants on the sixth year, 
when it was manured anew, than it was the first year. In the 
second year after manuring, it contained less mineral food than 
on the first year ; and after the fifth year it became so much ex- 
hausted that it was necessary, in order to obtain crops as rich as 
the first year, to give back to the field all the mineral constituents 
10 



194 RETROSPECT. 



that had been removed during the five years' rotation ; this was 
done, w^ithout doubt, by means of the manure. 

Our supply of manure, therefore, effects only this result, that 
the soil of our arable land is not rendered poorer than that of 
meadow land capable of yielding on the same surface 25 cwt. of 
hay. From a meadow we remove annually, in the hay, as great 
an amount of the constituents of the soil as we do in the crops 
obtained from the arable land; and we know that the fertility of 
meadow land is as dependent on the restoration of the constituents 
of the soil, as that of arable land is upon the supply of manure. 
Two meadows of equal surfaces, but containing unequal quantities 
of inorganic food, are of unequal fertility under like circumstances. 
The meadow containing the greatest quantity of the mineral food 
yields more hay, in a certain number of years, than the other 
which is poorer in mineral ingredients. 

But if we do not restore to a meadow the constituents of the 
soil removed from it, its fertility decreases. 

The fertility of a meadow remains the same, not only by treat- 
ing it with solid or with liquid excrements, but it may be retained, 
or may be even increased in fertility by the application of mine- 
ral substances left behind after the combustion of wood or of 
other plants. By means of ashes we can restore the impaired 
fertility of our meadow land. But by the term ashes, we un- 
derstand the mineral food which plants received from the soil. 
When we furnish them to our meadows we enable the plants 
growing on them to condense carbon and nitrogen on their surface. 

Now, does not the action of liquid and solid excrements 
depend on the same cause ? For these are but the ashes of 

PLANTS BURNT IN THE BODIES OF MAN AND OF OTHER ANIDIALS. 

Is fertility not quite independent of the ammonia conveyed to 
the soil ? If we evaporated urine, dried and burned the solid 
excrements, and supplied to our land the salts of the urine, and 
the ashes of the solid excrements, would not the cultivated plants 
grown on it — the graminese and leguminosiE — obtain their carbon 
and nitrogen from the same sources whence they are obtained by 
the gramiiieae and leguminoste of our meadows ? 

There can scarcely be a doubt with regard to these questions, 
when we unite the information furnished by science to that sup. 
plied by the practice of agriculture. 



INORGANIC MANURE. 



195 



The following rotation is adopted in Alsace, as oeing the most 
advantageous ; it extends over a period of five years, during 
which the land is only once manured : — 



1st Year. 



Potatoes or Wheat 

Beet 
Potash 
Plants. 



Clover 



4th Year. 

Wheat with 
Fallow turnips 



Silica 
Plant. 



Lime Silica 
Plant. Potash 



Plants 



5tlt Year. 6th Year. 
Manured. 
Oats, or 
Rye, or 
Barley. 

Silica 7 
Lime 3 



Potatoes 



Plants. 



Now, if we suppose that the action of the manure depends 
upon its ammonia, or amount of nitrogen, then it is obvious that 
a progressive diminution must ensue ; that the nitrogen in the 
crops of the first and second years must amount to more than 
that contained in the crops of the fourth and fifth years. But 
this opinion is completely opposed to the following proportions, as 
indicated by analysis : — 



Nitrogen in the crop 



1st Year. 
46 



2d Year. 3d Year. 
35-4 84-6 



4th Year. 
56-0 



5th Year. 

2S'4 



Thus, in the third and fourth years the nitrogen in the crops 
amounted to much more than the quantity contained in the crops 
of the first and second years ; and in the fifth year the quantity 
was only one-fourth less than it was in the second year. Now, 
is it possible or conceivable that the ammonia given in the first 
year, being a body of great volatility and very apt to evaporate 
along with water, could be present in greater quantity in the soil 
during the fourth year than it waa in the first and second years ; 
or that it could yield to the oats of the fifth year the necessary 
quantity of nitrogen for their growth ? 

But let us admit that the nitrogen conveyed to the soil by 
strong manuring was actually exhausted in the fifth year by the 
different plants cultivated upon it ; and let us then compare the 
rotation employed in Alsace, with that adopted on one of the 
most fertile districts of the Rhine. In Bingen there is a nine- 
years' rotation followed, the plants succjeeding each other in the 
following order : — 



196 RETROSPECT. 



1st year. 2d Year 3(1, 4th, 5th, 6th Years. 7th Year. 8th Year. 9th Year 

Manured. Manured. 

Turnips Barley with Lucern. Potatoes. Wheat. Barley. 
Lucern. 

Six year.s after manuring, after the supply of ammonia and 
manure containing nitrogen, after four succeeding crops of clover, 
and after a crop of barley and one of oats, the soil of Bingen 
yields rich crops of potatoes, wheat, and barley, and these suc- 
ceed each other at a time when, according to our assumption, the 
manured field in Alsace was to be viewed as completely e.x- 
hausted of its nitrogen. Can it be conceived that the ammonia 
of the manure could, after the lapse of 8 — 9 years, furnish the 
nitrogen to the crops of wheat and barley ? But even admitting 
this to be the case, we have then to inquire whence do the corn- 
fields in Hungary, in Sicily, or in the vicinity of Naples, receive 
their nitrogen, for these fields have never been manured ? Are 
we actually to believe that the nutrition of plants in the fields 
of moderate climates is subject to different laws from those 
governing the warmer and tropical regions ? 

In Virginia the annual crop of nitrogen in wheat amounted to 
22 lbs. an acre, on the smallest calculation, or in 100 years to 
2200 lbs. If we were to suppose that this nitrogen was fur- 
nished by the field, each acre must have contained it in the form 
of hundreds of thousand pounds of animal excrements ! 

The whole population of Limousin subsist upon milk and 
sweet chestnuts, the production of which, being unattended with 
trouble, is ascribed by Dupin as the cause of their low .state of 
intellect. Without being subjected to any system of farming, 
this district produces enormous quantities of the constituents of 
the blood, the nitrogen of which cannot have been produced from 
manure. 

For centuries, in Hungary, wheat and tobacco have been cul- 
tivated on the same field, without any supply of nitrogen. Is it 
possible that this nitrogen can have had its origin in the soil ? 
Our forests of beeches, chestnuts, and oaks, become covered with 
leaves every year ; the leaves, sap, the acorns, chestnuts, cocoa- 
nuts, the fruit of the bread-tree, are rich in nitrogen. This 
nitrogen is not contained in the soil, nor is it conveyed to the 



EXPERIMENTS OF BOUSSINGAULT. 197 

wild plants by the hand of man. Then it is impossible to doubt 
the source whence the nitrogen is obtained. The source of the 
nitrogen can only be the atmosphere. It matters not in what 
form it is contained therein, or in what form it is taken from it : 
the conclusion is the same, that the nitrogen of wild-growing 
plants must be derived from the atmosphere. 

Are the fields of Virginia, the fields of Hungary, our own cul- 
tivated plants, not able to receive it from the same sources as the 
wild-growing vegetation ? Is the supply of nitrogen in animal 
excrements a matter of absolute indifference : or do we obtain 

IN OUR FIELDS A QUANTITY OF THE CONSTITUENTS OF THE BLOOD, 
ACTUALLY CORRESPONDING TO THE SUPPLY OF AMMONIA ? 

These questions are completely solved by the investigations of 
Boussingault ; which are so much the more valuable, as they 
were instituted with a totally distinct object in view. 

From the known quantity of manure (common stable manure) 
which Boussingault put every five years upon his field (amount- 
ing to four Hessian acres), he estimated, by the analysis of the 
manure, the total quantity of nitrogen furnished for the rotation 
of five years. For this purpose, the moist stable manure was 
first dried by exposure to the air and to the sun, and afterwards 
was further dried in vacuo, by exposing it to a temperature of 
230° F. ; the manure thus treated was subjected to an ultimate 
analysis. The average crops of the field, treated with manure. 
Were then determined ; and the products, corn and straw, turnips, 
potatoes, peas, clover, &c., were analysed for the purpose of 
ascertaining their composition with reference to nitrogen, carbon, 
hydrogen, and ashes.* 

In this manner the quantities of nitrogen conveyed to the field 
in the form of manure, and reaped from it in the crops, were 
ascertained, and could be compared together. If the plants 
depended for their nitrogen upon the manure, and did not receive 
any of that element from the air ; the nitrogen of the crops could 

* The greatest number of these analyses — viz. the composition of pota- 
toes 'Boeckmann) ; of beet and turnips (Will) ; of wheat straw (Will) ; 
of the carbon and nitrogen of peas (Noll and Zytowieki); and of their 
carbon (Playfair), were repeated in this laboratory, and ascertained tc 
be perfectly correct. 



98 RETROSPECT. 



not correspond to more than the quantity in the manure. If the 
crops contained more than this quantity, the excess must have 
been obtained from other sources, and these could only be in the 
atmosphere ; such were the suppositions on which Boussingault 
proceeded. According to his estimation, the three rotations* 
yielded : — 

1st Rotation. 2d Rotation. 3d Rotation. In 16 years 
Nitrogen in lbs. - - - 501-4 50S-4 707'2 1717 
in stable manure - 406-4 406-4 487-6 13004 

Excess of nitrogen obtained, lbs. 95 10-2 2196 416-0 

In the first and second rotation, the excess of nitrogen obtained 
was nearly equal ; in the third it was twice as much. 

Now, asked Boussingault — did each of these plants possess the 
power of absorbing and appropriating to their organism nitrogen 
from the air, or was this power confined only to one of them ; and 
was the excess of nitrogen due to all the various kinds of plants, 
or was it yielded by only one of them ? A new experiment 
seemed to him to decide the question. Two successive crops of 
corn were taken from a fallow-field, well manured, and the pro 
duce amounted to : — 

Nitrogen in the crops - . . 174"8 lbs. 
the manure . ^ . 165 "6 

An excess of nitrogen - - 9-2 lbs. 

But this excess in the crop is too small not to be liable to errors 
in the experiment. Boussingault concluded from it, that cereals 
do not absorb nitrogen from the air, and that the amount of nitro- 
gen yielded in crops is only equivalent to that contained in the 
manures. 

Now, as it had been found that the quantity of nitrogen ob- 







1st Rotation. 


2d Rotation. 




3d Rotation. 


1 


Year 


Pot itoes 


Beet 




Potatoes 


2 


" 


Wheat 


Wheat 




Wheat 


3 


<« 


Clover 


Cl'wer 




Chn-er 


4 




Wheat ) 


Wheat 


) 


Wheat 




late Turnips 3 


late Turni 


ps 5 


late Turnips 


S 


u 


Oats 


Oats 




Peas 





(t 








Rye 



EXPERIMENTS OF BOUSSINGAULT. 199 

twined in crops of potatoes and turnips scarcely corresponds to 
more than tke quantity in crops of wheat, it follows that they 
could not have the power to form their azotized constituents with, 
out manure ; so that nothing remains, except to ascribe to the 
clover the excess of nitrogen obtained. This explains, also, why 
the excess is so much greater in the third rotation than in any of 
the preceding ; for it will be remarked, that in the third rotation 
a sixth crop was introduced, corresponding to the same family as 
clover. If, therefore, there had been neither peas nor clover in 
the third rotation, but, instead of these plants, one of another 
family, the nitrogen of the crop would have amounted only to the 
quantity supplied in the manure. Boussingault concludes that 
leguminous plants alone possess the power of appropriating, as 
food, nitrogen from the air, and that other cultivated plants do not 
at all possess this property. Hence the great importance which 
Boussingault ascribes to manures containing nitrogen, for, ac- 
cording to his view, the commercial value of a manure depends 
on its amount of nitrogen. But all these conclusions are tho- 
roughly erroneous ; for, if they were not so, it must follow that 
potash, lime, and silica plants, unless they belonged to the Legu- 
minosas, would not produce any nitrogen, unless they were sup- 
plied with manure containing that element. 

The conclusions of Boussingault are not only erroneous in their 
applications to agriculture, but are incorrect in the methods 
which he employs ; for the manure was not given to the fields in 
the form in which he analysed it. 

Let us assume that the manure which he put upon his fields 
possessed the same state in which it was analysed (dried at 
230° F. in vacuo) ; then the field would receive in the sixteen 
years 1300 lbs. of nitrogen. But the manure was not put upon 
tbe field in an anhydrous state, but, on the contrary, in its natu- 
ral moist condition, soaked with water ; and we know that all the 
nitrogen contained in the manure in the form of carbonate of am- 
monia is volatilized when it is dried at a high temperature. The 
nitrogen of the urine in the manure, which is converted by putre- 
faction into carbonate of ammonia, is not included in the 1300 lbs. 
of the above calculation. 

Human excrements, dried in the air at ordinary temperature 



800 RETROSPECT. 



(^poudretie), lose, at 230°, half of all the nitrogen contained in 
them, in the form of carbonate of ammonia. Common stable ma- 
nure, which contains 79 — 80 per cent, of water, must lose, when 
heated to 230° in vacuo, at least three times as much nitrogen 
as it retains ; that is, 3-4ths of all the nitrogen originally present 
in it. But if we estimate it at half of the quantity present in the 
dried excrements, then the field must have received, in sixteen 
years, 1950 lbs. of nitrogen. 

But in sixteen years, 1517 lbs. of nitrogen only were ob- 
tained, IN the form of corn, straw, and tubers ; much less, 
therefore, than the quantity furnished to the field. Hence his 
erroneous conclusion, that the Leguminosse alone possess the 
power of condensing nitrogen from the air ; and that it is neces- 
sary to furnish nitrogen to the Graminese, and to plants such as 
turnips and potatoes. But in the same time, and upon the same 
surface of a good meadow, not receiving nitrogen, we may obtain 
(on 1 hectare) 2060 lbs. of this element. 

It is well known that dried excrements form the principal fuel 
in Egypt, where wood is scarce. For centuries the sal ammo- 
niac used in Europe was supplied from the soot of these excre- 
ments, until Gravenhorst, in the latter part of last century, 
discovered how to prepare it, and instituted a manufactory at 
Brunswick. 

The fields in the valley of the Nile receive no manure of ani- 
mal origin except the fixed ingredients (which contain no nitro- 
gen) of the ashes of the burnt dung ; and yet these fields have 
been so fertile, for periods long before our history commences, 
that this fertility has become a proverb, and is quite as remarkable 
at the present day as it was in former times. These fields be- 
come renovated by the mud deposited during the inundations of 
the Nile ; the mineral ingredients of the soil removed in the crops 
are thus restored to it. The mud of the Nile contains as little 
nitrogen as the mud from the Alps, in Switzerland, deposited on, 
and fertilizing our own fields by the inundations of the Rhine. 

In fact, if the mud of the Nile fertilizes the soil, in consequence 
of its containing nitrogen, we must suppose immense strata of 
nitrogenized animal and vegetable matter to exist in the mountains 
of the interior of Africa, at heights above the line of perpetual 



REVIEW OF PRECEDING THEORIES. 201 

congelation, where, owing to tiie absence of all vegetation, no ani 
mal, not even a bird, can now find nourishment. 

Cheese must be formed from the plants upon which cows feed. 
The meadows of Holland must, of course, obtain their nitrogen 
from the air. The milch cows in Holland remain on the fields 
both day and night ; all the salts contained in their fodder 
must remain upon the fields in the form of urine and of solid 
excrements, a small quantity proportionately being removed in 
the cheese. 

The condition of fertility of these meadows can change as little 
as that of our fields, which, although not grazed upon, receive, in 
the form of manure, the greatest part of the ingredients removed 
from them. 

In the cheese districts of Holland, these ingredients remain on 
the meadows ; while in our system of farming, they are collected 
at home, and carried, from time to time, to our fields. The ni- 
trogen of the urine, and tlTat of the solid excrements of the cow, 
are obtained in Holland from the air ; and from the same source 
must be obtained the quantity of that element contained in all 
the kinds of cheese prepared in Holland, Switzerland, and other 
countries. 

The meadows in Holland, for centuries, have produced railliona 
of cwts. of cheese : there are annually exported from this country 
thousands of cwts. of this substance ; and yet this exportation 
does not in any way diminish the productivenessof their meadows, 
although they have never received from the hand of man more 
nitrogen than they originally contained. 

Hence it is quite certain, that in our fields, the amount of nitro- 
gen in the crops is not at all in proportion to the quantity supplied 
in the manure, and that the soil cannot be exhausted by the ex- 
portation of products containing nitrogen (unless these products 
contain at the same time a large amount of mineral ingredients), 
because the nitrogen of vegetation is furnished by the atmosphere, 
and not by the soil. Hence also we cannot augment the fertility 
of our fields, or their powers of production, by supplying them 
with manures rich in nitrogen, or with ammoniacal salts alone. 
The crops on a field diminish or increase in exact proportion to 
10* 



202 REVIEW OF PRECEDING THEORIES. 

the diminution or increase of the mineral substances conveyed to 
it in manure. 

The formation of the constituents of the blood, and of the vege- 
table substances containing nitrogen existing in cultivated plants, 
depends upon the presence of certain substances contained in the 
soil. When these ingredients are absent, nitrogen will not be 
assimilated, however abundantly it may be supplied. The am- 
monia of animal excrements exerts a favorable influence only 
because it is accompanied by other substances necessary for its 
conversion into the constituents of blood. When these conditions 
are furnished with ammonia, the latter becomes assimilated. But 
when the ammonia is absent from the manure, the plants extract 
their nitrogen from the ammonia of the air ; to which it is again 
restored by the decay and putrefaction of dead animal and vege- 
table remains. 

Ammonia accelerates and favors the growth of plants on all 
kinds of soil, in which exist the conditions for its assimilation ; 
but it is quite without action upon the production of the consti- 
tuents of the blood, when these conditions do not exist. 

It is possible to conceive that asparagin (the active ijigredient 
of asparagus) and the ingredients so rich in nitrogen and sulphur, 
of mustard and of all Cruciferse, could be generated without the 
co-operation of the ingredientsof the soil. But if it were possible 
to form the organic constituents of blood existing in plants, with- 
out the aid of the inorganic ingredients of the blood, such as 
potash, soda, phosphates of soda and of lime, they would be of 
very little use to animals, and could not fulfil the purposes for 
which they were destined by the wisdom of the Creator. Blood, 
milk, and muscular fibre cannot be formed without the aid of 
alkalies and of phosphates ; and bones cannot be produced without 
phosphate of lime. 

In urine, and in the solid excrements of animals, and in guano, 
we furnish ammonia, and therefore, nitrogen, in our plants. 
This nitrogen is accompanied by the mineral food of plants, and 
actually in the same proportion as both exist in the plants which 
served the animals for food ; or, what is the same thing, in the 
same proportion in which both are capable of being applied for a 
new generation of plants. 



REVIEW OF PRECEDING THEORIES. 203 

The action of an artificial supply of ammonia as a source of 
nitrogen, is limited, like that of humus as a source of carbonic 
acid, to a gain in point of time ; in other words to the ac- 
celeration of the development, in a given time, of our cultivated 
plants. 

By means of ammonia, in the form of animal excrements, we 
increase the quantity of the constituents of blood in our cultivat- 
ed plants — an action which the carbonate or sulphate of ammonia 
alone never exerts. 

In order to obviate any misunderstanding, we must again draw 
attention to the fact that this explanation is not in any way con- 
tradicted by the effects produced on the application of artificial 
ammonia, or of its salts. Ammonia is, and will continue to be 
the source of all the nitrogen of plants : its supply is never in- 
jurious ; on the contrary, it is always useful, and, for certain 
purposes, indispensable. But, at the same time, it is of great 
importance for agriculture, to know with certainty that the sup- 
ply of ammonia is unnecessary for most of our cultivated plants, 
and that it may be even superfluous, if only the soil contain a 
sufficient supply of the mineral food of plants, when the ammonia 
required for their development will be furnished by the atmo- 
sphere. It is also of importance to know, that the rule usually 
adopted in France and in Germany of estimating the value 
of a manure according to the amount of its nitrogen, is quite 
fallacious, and that its value does not stand in proportion to its 
nitrogen. 

By an exact estimation of ihe quantity of ashes in cultivated 
plants, growing on various kinds of soils, and by their analysis. 
we will learn those constituents of the plants which are variable, 
and those which remain constant.* Thus also we will attain a 

* The following analyses of ashes may be added to those formerly given : 



Silica - - - 
Sulphate of potash 
Chloride of sodium 
Carbonate of potash 
Carbonate of soda 
Carbonate of lime 



Ashes of Clover 
( Tr^olium pratense). 

- 5 -438 


Ashes of 
Sainfoin. 

2-79 


- 3-OSO 


3S7 


- 1-670 


2-37 


- 12-728 


9-93 


- 13-528 


17-16 


- 38-216 


32-55 



204 REVIEW OF PRECEDING THEORIES. 

knowledge of the quantities of all the constituents removed fronj 
the soil by different crops. 

The farmer will thus be enabled, like a systematic manufac- 
turer, to have a book attached to each field, in which he will 
note the amount of the various ingredients I'emoved from the land 
in the form of crops, and therefore how much he must restore to 
bring it to its original state of fertility. He will also be able to 
express in pounds weight, how much of one or of another ingre- 
dient of soils he must add to his own land, in order to increase its 
fertility for certain kinds of plants. 

These investigations are a necessity of the times in which we 
live ; but in a few years, by the united diligence of chemists of 
all countries, we may expect to see the realization of these views ; 
and by the aid of intelligent farmers, we may confidently expect 
to see established, on an immovable foundation, a rational system 
of farming for all countries and for all soils. 





Ashes of Clover 


\shes of 




{Trifolium pratcjise.^. 


Sainfoin. 


Magnesia - - 


- 4-160 


9-11 


Phosphate of iron 


- 1-240 


0-64 


Phosphate of lime 


- : 1-970 


15-37 


Phosphate of magnesia 


- 6-790 


3-98 


Carbonaceous matter - 


- 0-160 


0-36 



98-950 98-1.^ 



SOU-RCES OF AMiMONIA. 203 



SUPPLEMENTARY CHAPTERS. 

I. — The Sources of Ammonia. 

When animals appeared on the surface of the earth, it cannot be 
doubted that means must have been provided for their sustenance 
and increase, or in other words, that plants must have existed to 
furnish them with food. But it is quite as obvious that, at the 
period of the formation of the vegetable world itself, the condi- 
tions must have existed in the soil and in the atmosphere, neces- 
sary for the exercise of vegetable life. With the same certainty 
with which we presuppose the existence of a compound of carbon 
to furnish that element to vegetation, we must also assume the 
contemporaneous presence of a compound of nitrogen, such as at 
the present day yields that element to plants. 

If we disregard the fundamental principle on which all 
inquiries into nature ought to proceed, then we may assume, 
a priori, according to our will and pleasure, that other compounds 
of carbon, differing from carbonic acid, formerly took part in the 
vital processes of plants ; but if we still retain the foundation of 
all scientific inquiry, namely, induction from facts, then we can- 
not admit the existence of these hypothetical compounds of car- 
bon, either because they are totally unknown to us, or that their 
existence is doubtful. 

The same reasoning must be adopted in the case of nitrogen. 
Science is at present ignorant of any compound of nitrogen be- 
sides ammonia, capable of yielding nitrogen to wild plants on all 
parts of the earth's surface. No other such compound of nitrogen 
has been indicated, or even hypothetically supposed to exist, and 
designated by a name, in the case of cultivated plants ; and there- 
fore, until a second source of nitrogen is discoveredj we must, ia 
science, view ammonia as the only source. 



206 SOURCES OF AMMONIA. 

Now, it may be asked, Is there no means of increasing the 
amount of ammonia which exists in the atmosphere, as well as 
in the form of plants and animals, and which we shall assume tc 
be a limited quantity ? This question may be repeated in another 
form, viz. Whether there exist undoubted facts for the opinion 
that the nitrogen of the air possesses, under any condition, the 
power of assuming the form of ammonia, or of any other com- 
pound of nitrogen ? Besides nitric acid and ammonia, we do 
not know any other compounds of nitrogen, except those exist- 
ing in plants and animals, or which may be prepared from them. 
With the exception of these compounds, nitrogen exists only in 
the form of a gas, which has been recognised as one of the prin- 
cipal constituents of air. 

An ignorance of the proper sources whence vegetation receiv- 
ed its nitrogen, led philosophers long since to the opinion, that 
plants must possess the power, in some way or another, of appro- 
priating the nitrogen of the air in their vital processes. In fact, 
until it was known that ammonia formed a constituent of the air, 
there was scarcely any reason to doubt this power of plants ; for 
how otherwise were wild plants to obtain the nitrogen of their 
azotized constituents ? 

But ammonia was known and considered only as a product of 
the destruction and decomposition of the organism. The pro- 
duction and formation of ammonia presupposed the existence of 
plants or animals. Hence there have arisen two views respect- 
ing the origin of ammonia, the correctness of which we have as 
little means of establishing by decisive evidence, as we have of 
answering the questions — Whether the hen existed before the 
egg, or the egg before the hen ; or whether water was first creat- 
ed as water, or as hydrogen and oxygen ? We have sufficient 
reason to believe that the vegetable preceded the animal kingdom ; 
and we assume, that before plants were formed, the conditions 
essential for their life and increase must have existed ; and that 
then, as well as now, ammonia must have been a constituent of 
the air ; and that the destruction of plants did- not precede the 
formation of ammonia. Now, it is obvious that if the same 
causes now continue in action, as those which effected the forma- 
tion of ammonia at the commencement of vegetation, — if their 



FORMATION OF MATTER. 20": 

action resulted in the conversion of the gaseous nitrogen into 
ammonia, — then, at the present day, during every moment, am- 
monia must be forming, and the amount of that previously exist- 
ing will be increased. It is natural to the mind of man to 
ende-avor to solve questions of this kind, however small may be 
the expectation of success. It is known that the crust of the 
earth consists of compounds of oxygen with metals or with other 
radicals ; and the view appears quite admissible, that silica has 
been formed from silicon and oxygen ; peroxide of iron from 
iron and oxygen ; and, to follow up the idea, magnesia and potash 
have been produced from oxygen, magnesium, and potassium. 
And yet it is utterly impossible to assign a cause which prevent- 
ed the union of the oxygen with potassium or magnesium before 
the time that this combination actually took place. Was there, 
it may be asked, a time when the individual elements floated to- 
gether in Chaos, without possessing any kind of affinity ? In 
what condition then was the chlorine of common salt or the carbon 
of carbonic acid ? It is obvious that no answers can be given to 
questions respecting the origin of matter. If, then, we are una- 
ble to afford any more satisfactory explanation of the origin of 
ammonia, than we are able to do of the other compounds occur- 
ring upon the earth, we must rest satisfied that these questions 
will either never be solved, or that they will not be so until a 
future period. 

The ferruginous earths in the primitive rocks of South Ame- 
rica (Boussingault), and of Sweden (Berzelius), — in fact all 
ferruginous earths hitherto examined, — yield, on being heated, 
a certain amount of water containing appreciable quantities of 
ammonia. Whence has this ammonia had its origin ? Accord- 
ing to the logic of Aristotle, the occurrence of ammonia in the 
ferruginous earths was susceptible of a satisfactory explanation. 

We may assume that water is the only original compound of 
hydrogen occurring in nature ; other bodies containing that ele- 
ment are products of the decomposition of water, from which 
they have procured this hydrogen. 

Ammonia has been formed like other compounds of hydrogen ; 
the ferruginous eaith was formerly iron, which we may suppose 
to have become oxidized at the expense of water, in which case 



208 SOURCES OF AMMONIA. 

peroxide of iron would be formed, and hydrogen become liberal 

ed. Now, if we assume that hydrogen, at the moment of its 
liberation, is able to unite with nitrogen gas in contact with it, 
and dissolved in water, then ammonia would be produced, and 
would remain in union with the peroxide of iron. It is certain 
that thij explanation of the origin of ammonia in peroxide of 
iron would be perfectly satisfactory, if it were ascertained 
with some degree of probability that peroxide of iron has 
had its origin by oxidation at the expense of water, and that 
the nitrogen of air is capable of uniting with hydrogen at 
the instant of its liberation. On this view we might suppose, 
that although there was a limit to the formation of ammonia, 
under former conditions, when ferruginous earth was produced, 
that by the simultaneous occurrence of the same or of analogous 
conditions at the present day, ammonia might still be produced. 

But the decomposition of water, by means of iron, is effected 
under such circumstances as appear to exclude the simultaneous 
production of ammonia. 

Iron does not decompose water at the ordinary temperatures, 
and at higher temperatures — at the boiling point of water, for 
example — nitrogen does not remain any longer in solution. When 
a stream of nitrogen is made to pass along with water over iron 
filings heated to redness, the nitrogen is again obtained unaltered 
although it be mixed with hydrogen. It is easily explained why am- 
monia cannot be formed in this case, for ammoniacal gas in contact 
with iron at high temperatures, is decomposed into its constituents. 

When finely divided hydrate of peroxide of iron is placed in 
contact with metallic iron, a decomposition of water takes place 
at a slightly elevated temperature, and hydrogen gas is evolved, 
while magnetic oxide of iron is produced. As hydi-ated peroxide 
of iron acts as an acid in this case, we should here, as indeed 
ijniversally, when metals are dissolved in acids Avith the evolution 
of hydrogen, obtain in the solution a salt of ammonia, if ammonia 
had been formed. 

But hitherto the presence of ammonia under the circumstances 
has not been detected ; and it has further been shown satisfactorily, 
that when water holding air in solution is decomposed by a stream 
of pleptricity, the hydrogen evolved is accompanied by a certain 



RELATION OF NITROGEN TO HYDROGEN. 203 

quantity of nitrogen gas, which could not be the case if nascent 
hydrogen were able to form ammonia. 

It has been considered as a certain proof of the formation of 
ammonia from the nitrogen of the air, that peroxide of iron, 
formed by the rusting of iron in the air, contains a certain quan- 
tity of ammonia ; but air itself contains ammonia, which pos- 
sesses a considerable affinity for peroxide of iron. Marshall 
Hall has shown the inaccuracy of the view that water is decom- 
posed in this case ; and further experiments, instituted in this 
laboratory for the especial purpose of deciding this question, have 
shown, that when air is freed from its ammonia, by being con- 
ducted through concentrated sulphuric acid, befora being brought 
in contact with the rusting iron, the oxide then formed does not 
contain a trace of ammonia. 

Braconnot* has shown that most basalts, trap, granite from 
Rochepon, and from Bresse ; syenite, amphibolite, wakit (a lava) ; 
basalt, from Baden ; quartz, from Gerordines ; pegmatite, and 
many other minerals, yield, by dry distillation, water containing 
a sensible quantity of ammonia. 

These facts cannot be explained by the interpretation above 
given to the occurrence of ammonia in ferruginous earth, namely, 
the oxidation of iron at the expense of water ; but there cannot 
be any doubt that the ammonia has had a similar origin in all 
these cases, although that origin cannot be ascribed to an oxida- 
tion of iron. 

The question — whether the nitrogen of the air possesses the 
power of uniting with hydrogen at the moment of its liberation 
from water ? has been lately made the subject of exact experi- 
ments, although with very different objects in view. Will and 
Varrentrapp applied to the quantitative estimation of nitrogen in 
organic bodies the known fact, that the nitrogen of bodies con- 
taining that element is evolved in the form of ammonia, when 
they are heated to redness, mixed with potash. By combining 
the ammonia with an acid, and converting it into the salt termed 
chloride of platinum and ammonia, the ammonia generated may 
be weighed with ease, and the quantity of nitrogen may 
be calculated from the known composition of this salt. A great 
* Annates de Chiinie et de Physique, tcme Ixvii., p. 101, &c 



210 SOURCES OF AMMONIA. 

number of analyses of compounds, in which the quantity of ni- 
trogen was known, showed that this mode of procedure answered 
completely the object in view ; until certain experiments by 
Reiset were published, in which he obtained ammonia by this 
process from substances such as sugar, &c., which were quite 
destitute of nitrogen. Reiset, therefore, assumed that the nitro- 
gen of air contained in the pores of the mixture was the cause of 
the formation of ammonia, and that, unless this air were excluded, 
the method of analysis was incorrect and objectionable. 

New experiments, repeated with the utmost care by Will, have 
shown that in circumstances similar to those formerly observed 
by Faraday, ammonia is actually obtained from matters destitute 
of nitrogen, when they are heated to redness with potash ; but 
that, by excluding ammonia itself, nitrogen cannot be made to 
unite with hydrogen in a nascent state, and that ammonia can- 
not be produced from these elements. 

The admirable experiments of Faraday (Quarterly Journal of 
Science, xix., p. 16) prove that, in all the cases in which ammonia 
was obtained by heating to redness a substance destitute of nitro- 
gen with hydrate of potash, the ammonia existed ready formed 
in the substance, or in the hydrate of potash. There are no ob- 
servations more convincing of the extraordinary diffusion of am- 
monia, which exists in all places where atmospheric air is to be 
found. That the reader may judge properly of Faraday's experi- 
ments, I consider it important to describe them here in detail. 

After Faraday had observed that woody fibre, linen, oxalate of 
potash, and a number of other substances free from nitrogen, 
evolved ammonia on being heated with soda, potash, hydrate of 
lime, &c., he endeavored to ascertain the conditions under which 
the formation of ammonia ensued ; and in the first place, he ex- 
amined the alkalies. Hydrate of potash, whether made from 
potashes, cream of tartar, or potassium, behaved exactly in the 
same manner. The organic substances, when heated alone, had 
no reaction on turmeric ; but when heated with the alkalies, a 
disengagement of ammonia ensued. 

It was then to be supposed that the nitrogen of the air sur- 
rounding the substances might take a part in the formation of 
ammonia : but this was very improbable : for it is known that 



FARADAY'S EXPERIMENTS. 21/ 

die air contains oxygen, which was never observed to unite with 
the liberated hydrogen under the same circumstances, altliovigb 
its affinity for that element is infinitely greater than for nitrogen. 

According to this supposition, the nitrogen of the air must 
have formed ammonia by uniting with the hydrogen of the 
decomposed water, although at the same time there was present 
oxygen, for which hydrogen has a much greater affinity. 

The experiments were repeated in an atmosphere of pure hy- 
drogen, prepared from water which was previously freed from 
all air by long-continued boiling. But in this case also, where 
all nitrogen was excluded, the presence of ammonia was observed". 
Hence, Faraday concluded that there must be an unknown 
cause of the formation of ammonia. 

Now, when it is known that ammonia is a constituent of the 
air ; that it is present wherever the air is found ; that it is itself 
a coercible gas, which is condensed on the surface of solid bodies 
in much larger proportion than air ; and further, when it is 
known that it exists in distilled water, these, and other still more 
incomprehensible experiments of Faraday, are explained in a very 
simple manner. 

Fine and bright iron wire, introduced into fused potash, causes 
the evolution of ammonia, which soon ceases; but a new evolu- 
tion takes place when a second portion of polished iron-wire is 
introduced (Faraday). 

Zinc introduced into potash in a state of fusion, occasions an 
immediate evolution of ammonia and hydrogen gas ; but althoug,h 
the conditions for the possible formation of ammonia continue 
(zinc, air, and nascent hydrogen), the quantity of ammonia gene- 
rated does not increase ; but, by the addition of fresh zinc, or 
of hydrate of potash, a new quantity of ammonia may be 
detected. 

Some potash and zinc were heated together ; a part of the mix- 
ture was then placed in a flask, which was immediately closed, 
while another part was dissolved in water, the clear solution dried, 
and laid aside for 24 hours. After this time had elapsed, the 
first portion gave scarcely perceptible traces of ammonia. The 
other gave very appreciable indications of its presence, apparently 



212 SOURCES OF AMMONIA, 

as if the substances which were the source of ammonia were 
derived from the air, during the operation (Faraday). 

White clay from Cornwall, after being heated to redness and 
exposed for a week to the air, yielded ammonia abundantly, when 
heated in a tube. But when the clay was preserved in a good 
stoppered bottle, after being heated to redness, this effect was not 
produced. 

The observations which proved most undoubtedly that in all 
these cases the ammonia was obtained from the air and condensed 
on the surface of these materials, are the following (Faraday) : — ■ 

Sea-sand was heated to redness in a crucible, and allowed tc 
cool on a plate of copper ; 12 grains of the sand were then 
placed in a clean glass tube ; and an equal quantity, shaken upon 
the hand, was allowed to remain there for a few moments, being 
stirred about with the fingers, after which it was introduced into 
a second tube by means of platinum foil, taking care that the 
grains of sand were not brought in contact with any other animal 
substance (Faraday). 

When the first tube was heated, it gave no sign of ammonia 
to turmeric paper ; but the second tube did so in very appreciable 
quantity. For the sake of precaution the tubes used in these 
experiments were not cleansed by tow or cloth, but unused tube? 
were taken, and before being employed they were heated to 
redness in a stream of air (Faraday). 

Some asbestos heated to redness, and introduced into a tube 
with metallic tongs, gave, when heated, no indication of ammonia ; 
while, on the contrary, another portion, which had been simply 
pressed with the finger, yielded immediate indications of am- 
monia when heated in a tube (Faraday). 

Now it is known that ammonia evaporates by the skin, that 
sweat contains salts of ammcnia ; and nothing can be more certain 
than that, in the experiments last described, and also in those of 
the burnt sand exposed to air, ammonia must have condensed on 
tlie surface of the sand or of the asbestos. 

These experiments explain in a natural manner the existence 
of ammonia in earth from which plants and animals are entirely 
absent, and also of the formation of nitre in mixtures of earths 
containing vegetable matter. 



FARADAY'S EXPERIMENTS. 213 

All observations in our times lead to the conclusion that the 
nitrogen of the air does not possess the property of being con- 
verted into ammonia ; and, whatever reasons there may exist for 
the probability of this conversion, we are by no means entitled 
to elevate to the rank of a principle the mere opinion that a part 
of the nitrogen of plants arises from this source, as it is an hy- 
pothesis standing in complete contradiction to all the knowledge 
which we have yet attained. 

All experiments which appear to piove that the nitrogen of the 
air becomes fixed in the organism of certain plants, — that peas 
and beans, for example, vegetating in a soil perfectly destitute of 
animal matters, must possess the power of appropriating the ni- 
trogen of the atmosphere, — cannot now have the smallest value, 
when it is known that the air contains ammonia as a constant 
ingredient. It must be recollected that these experiments were 
instituted in districts in which the atmosphere is much richer in 
ammonia than in the free fields, and that the distilled water, with 
which the plants were treated, was obtained from spring-water, 
and contained a much larger quantity of carbonate of ammonia 
than rain-water. Hence, there is no reason to ascribe the in 
crease of nitrogen in the seeds, leaves, and stems, to a source 
which was only imagined to exist, because the quantity of am- 
monia in the water and air was not considered, and the founda- 
tion, therefore, of the true explanation was altogether wanting. 

Chemical experiments have shown that ammonia is not only the 
product of the decay and putrefaction of animal bodies, but that 
it is also capable of being generated in many cliemical processes, 
when nitrogen, at the moment of its liberation from compounds 
containing it, is offered to hydrogen ; in such a case, they unite 
together and form ammonia. 

Compound gases containing nitrogen as a constituent (cyanogen, 
nitric oxides, nitrous oxides), are converted into ammonia when 
they are mixed and conducted over spongy platinum heated to 
redness (Kuhlmann), or over peroxide of iron (Reiset). 

When steam is conducted over red-hot wood charcoal contain- 
ing nitrogen, there is obtained, among other products, hydrocyanic 
acid, which is converted into ammonia and formic acid when 
treatea with alkalies. 



214 IS NITRIC ACID FOOD FOR PLANTS ? 

The nitrogen of nitric acid, when placed in contact with hydro- 
gen at the moment of its liberation, as in the solution of tin, or by 
fusing nitrates with potash and organic substances, is converted 
into the compound of hydrogen. In all cases in which we expose 
to a high temperature a body containing nitrogen and caustic 
potash, its nitrogen assumes the form of ammonia. 

The nitrogen of an organic body, of vegetable or animal mat- 
ter, or of the charcoal produced from them, arises from the am- 
monia which the plant contained and abstracted from the atmo- 
sphere : it enters, in the processes of decomposition alluded to, into 
its original form, and assumes the condition of ammonia. 

But these instances cannot be cited as proper examples of the 
formation of ammonia, nor can they be considered with reference 
to the question which we have now been discussing. 



IS NITRIC ACID FOOD FOR PLANTS ? 

Befoke we can examine the opinion whether nitric acid be a 
means by which nitrogen is furnished to plants in nature, it is 
most important to consider the origin of nitric acid. 

At the request of the French Government, the Academy of 
Sciences of Paris, in -.he year 1770, offered a prize for the best 
treatise on the formation of nitric acid and its production in arti- 
ficial nitre-beds. The judges appointed by the Academy, includ- 
ino- Lavoisier, subjected to trial 70 treatises, the results of which, 
after the experience of 50 years, were stated in a small work 
published by Gay Lussac, in the year 1825,* in the following 
sentences': — 

1. " All the nitrogen necessary for the formation of nitric acid 
is yielded to it by animal matter." 

2. " Nitre is never generated from the air in substancea 

* Instruction sur la fabrication du salpetre, publii par la Commission 
(lea poudres et salpitres, 1S25 



FORMATION OF NITRE. 213 

adapted for its formation, without the co-operation of anima 
matter." 

This result of very numerous and correct experiments contra- 
diets completely the view that nitre may be generated in mixtures 
of earth destitute of animal matter, and therefore at the expense 
of the constituents of the air. The advocates of this view cite in 
defence of it the following experiments : — When earth forming 
nitre is freed from all its soluble salts by lixiviation, and is then 
exposed for several years to the action of the air, it yields a se- 
cond crop of nitre, and these crops may be obtained three or four 
times in succession, although in different proportions. The ad- 
vocates of this theory, considering that all the substances con- 
taining nitrogen are removed, argue that the nitrogen of the nitre 
formed afterwards, must have been derived from the air. But 
this conclusion is opposed to all rules of inductive science. When 
a known cause produces the same action in all cases submitted 
to examination, we must revert to the same cause in considering 
the same action in cases not examined ; for we have no right to 
assign to it a new cause, in order to save us the trouble of a 
closer investigation. 

The advocates of the opinion that the nitrogen of the air is con- 
verted into nitric acid in the nitre-beds, have never estimated the 
amount of substances containing nitrogen existing in those beds ; 
and they have never compared with this amount the quantity of 
nitric acid actually generated. Those who, like Gay Lussac, 
have taken this trouble, found that the quantity of nitric acid 
formed corresponded to the quantity of animal matters present in 
the mixture ; less nitre being formed, when the amount of the 
latter was decreased, and by its increase, a greater quantity of 
nitre was produced. 

Another reason for the opinion was, that nitrates were formed 
in certain limestone caverns in Ceylon, where, according to Dr. 
Davy, nitrates of potash and lime occur in a limestone containing 
felspar, but quite destitute of animal matter. But the latter as- 
sertion is very questionable, as there is scarcely a limestone in 
existence that does not yield ammoniacal liquid on being subjected 1 1 
to distillation. An experiment with materials expressly prepared ' 
for this purpose (carbonate of lime, felspar, and water free from 



218 IS NITRIC ACID FOOD FOR PLANTS ? 

ammonia), and conducted in this cavern, in order to see whether 
nitric acid would be formed, would have completely decided the 
question, if nitric acid had been found in the mixture after a cer- 
tain time ; but this experiment was not made, neither was the 
water which filtered through the roof of the cavern subjected to 
examination. The conclusion that nitric acid is formed in these 
cases, at the expense of the nitrogen of the air, is not in any way 
confirmed — it is only certain that the cause of the formation 
of nitre in these caves remains unknown to those who have ex- 
amined them. 

It often happens that the well-water of towns contains a con- 
siderable quantity of nitre which does not exist in the wells and 
springs outside the towns. Berzelius detected nitrates in the well- 
water of the city of Stockholm. Margraf also mentions its ex- 
istence ; and I, myself, have shown the presence of nitrates in 
the waters of twelve wells in the town of Giessen,* although they 
could not be detected in the waters of six wells separated 2300 
paces from the town. Animal matter, in a state of decay and 
putrefaction, existed abundantly in the soil in all the places where 
nitrates were found, and its nitrogen was converted into ni- 
tric acid wherever the conditions for this conversion were found 
united. 

A large proportion of the nitre used in France, for the manu- 
facture of gunpowder and for other purposes, is obtained at Paris. 
The manufacturers of nitre use in its preparation the lower par's 
of old broken-up houses, which have been in constant contact 
with the liquids of the street. Nitre exists in large quantify in 
the lower parts of houses, while the upper parts do not contain a 
trace of it. 

It cannot be denied that plants grow more powerfully and 
luxuriantly in a soil capable of forming nitre, than they do in a 
soil unfit for its formation. 

The favorable influence of such a soil on vegetation is justly 
ascribed to the animal matters contained in it, to the alkalies, and 
to the phosphates existing in the animal matter. Out of the ani- 
mal matter also, is formed the ammonia so necessary for the sup. 

* Annales de Chiniie et Je Physique, vol. >^xxv., 232. 



FORMATION OF NITRE. 2l7 

port of vegetation, and without the presence of which nitric acid 
could not be formed. 

The presence of alkaline nitrates in a soil indicates with the 
greatest certainty, that the most important conditions for the 
growth of plants are united in it ; but these salts are not the pri- 
mary causes of the gi'owth, because both the formation of nitre, 
and the luxuriant growth of plants, are effects of similar causes 
acting on the earth. It is certain that the vicinity of the saltpetre 
mines of Quarta Jaga and Santa Rosa, described by Darwin, 
although saturated with nitrates, forms a complete waste, in which 
a small cactus is scarcely able to grow. The cause of its sterility 
may be the want of rain ; but if it were moist, and obtained 
abundant supplies of rain, the nitrates would have disappeared 
long since ; and, even without their presence, vegetation would 
flourish luxuriantly in this climate. 

The common error is to confound a soil, in which nitrates 
EXIST, with one in which they are in the act of forming. If the 
first soil be wanting in the conditions (animal matter) necessary 
for a further formation of nitric acid, it will prove sterile, but 
will, on the contrary, be fertile if these conditions exist. The 
latter, and not the nitrates, are therefore the causes of the better 
growth of vegetation. 

It follows from the preceding observations, that, as far as our 
experiments extend, the formation of nitric acid on the surface of 
the earth, is dependent on the presence of animal matter. 

But as animal substances receive their nitrogen from the 
atmosphere in the form of ammonia, the primary origin of the 
nitric acid of nitrates must be the ammonia of the atmosphere. 
But it may be affirmed, in addition to this, that ammonia is not 
the only ultimate source of, but that it is actually the immediate 
source of nitric acid. We have reason to believe that the nitro- 
gen of decaying animal substances assumes the form of ammonia, 
before being converted into nitric acid ; and that it must first be 
in the state of ammonia, before it is able to form nitric acid with 
the oxygen of the air.* Hence we must view ammonia as the 
principal source of the formation of nitric acid on the surface of 

• See the Chapter on Eremacaiisis in se'^ond part of this book. 
11 



918 IS NITRIC ACID FOOD FOR PLANTS ? 

the earth ; and we may expect the production of the latte? 
wherever ammonia, and the conditions for its oxidation, are 
found united. 

The occurrence of large beds of nitrates in America cannot 
afford the most distant reason for the assumption that they are 
formed in an unusual way ; it is unnecessary to call in the as- 
sistance of the nitrogen of the air, in order to explain their great 
extent. We find in nature whole mountains consisting of shell- 
fish, and of remains of microscopical animals, which must have 
contained a certain quantity of nitrogen when alive. We find 
also large layers of animal excrements (Coprolites), which place 
beyond all doubt the former existence of innumerable individuals 
of species now extinct. In the processes of decay and putrefac- 
tion to which they have been subjected, the nitrogen of their 
bodies could have escaped only in two forms ; in cold climates, 
it would assume the form of ammonia, and in warmer countries, 
the form of nitric acid, which must accumulate wherever the 
salts formed by means of it are not carried off by water. 

Ammonia, however, is not the only source of the formation of 
nitric acid. In the action exerted by the electric spark on the 
constituents of air (which are also the constituents of nitric acid), 
we recognise a second source, which, to all appearance, is very 
extended. 

Cavendish was the first to observe, that by a continued passage 
of electric sparks through moist air, its volume diminished, and 
an acid, soluble in water, was formed at the same time. This 
great philosopher proved, by a series of decisive experiments, 
that the constituents of the air, the nitrogen and oxygen, united 
to form nitric acid when exposed to the influence of electricity. 

Now it is probable that lightning (the most powerful electric 
spark known), in its passage through moist air, may effect a com- 
bination of the constituents of air, in consequence of which nitric 
acid would be formed. 

In an examination of rain-water, which the author of the 
present work undertook in the years 1826-1827 (Annales de 
Chimie et de Physique, xxxv., 329), it was actually found that 
out of seventy-seven analyses made of the residue of rain-water, 
seventeen of them, obtained by the evaporation of the rain of 



FORMATION OF NITRIC ACID. 219 

thunder-storms, contained more or less nitric acid, partly in com- 
bination with lime, and partly with ammonia. In the sixty others, 
only two contained traces of nitric acid. 

The occurrence of nitric acid in rain-water as nitrate of 
ammonia, renders it uncertain whether the nitrogen of the former 
was obtained from the atmospheric air itself, or from the ammonia 
existing in it, in the state of a gas. Henry observed that ammo- 
niacal gas, mixed with oxygen, and exposed to electric sparks, is 
likewise converted into nitric acid. It is obvious, that, if the 
rain contains carbonate of lime mechanically mixed with it in the 
form of dust, the nitrate of ammonia also present will be con- 
verted during evaporation into carbonate of ammonia, which vcill 
escape, and into nitrate of lime, which remains in the residue. 
The quantity of nitric acid contained in the rain of a thunder- 
storm cannot be estimated. Two or three hundred pounds of 
filtered rain-water yield only a few grains of a colored residue, 
and the nitrates contained in the latter form only a fractional 
part of its weight. 

The analysis of the water of springs and of rivers is much 
better adapted to give us a clear conception of the quantity of 
nitric acid formed by the influence of electricity in the atmo- 
sphere. If we suppose the nitric acid to exist in water in a free 
state, as it is a volatile acid, it must escape during the evapora- 
tion of the water in porcelain vessels, so that the residue will not 
contain a trace of it, if the bases necessary for its fixation be 
deficient. The water of our springs, streams, and rivers, is rain- 
water, which, if nitric acid were originally present in it, must 
now contain nitrates, by filtering through the earth, which in- 
variably contains lime and alkaline bases. 

It follows, from the interesting observations made by Gobel, in 
his journey to Southern Russia, that, by the evaporation of the 
river Charysacha, which falls into the lake Elton, the latter must 
receive annually 47,777 millions of pounds of salts. The water 
of the Charysacha contains scarcely 5 per cent, of salts ; so some 
conception may be formed of the quantity of water which must 
evaporate, in order to furnish the above quantity. The river has 
its source about forty wersts from Lake Elton, and obtains its 
water from the rain and snow falhng on the mountains. 



220 IS NITRIC ACID FOOD FOR PLANTS > 

If nitric acid be a constant and generally appreciable consti. 
tuent of rain-water, it is obvious that we ought to find sensible 
traces of it in the mother liquor remaining behind after the crys- 
tallization of the salt. But Gobel did not observe the presence 
of nitrates either in the water of the river or in the deposited 
salt. 

In the water of the Artesian Well* of Grenelle ; in the water 
of the Nile ;t in that of the Seine, which contains carbonate of 
ammonia in dry seasons ; in the waters of the Thames, or of the 
Rhine, no one has yet proved the presence of nitrates. 

We may assume, from these facts, that the nitric acid fur- 
nished to the earth in Europe, by means of rain, is extremely 
small in amount ; so that, even if the nitric acid formed by light- 
ning exercise a favorable action on vegetation, still this influence 
cannot be considered as a source of the nitrogen of plants. When 
it is considered that the number of thunder-storms in a year does 
not amount in some districts to above twelve on an average, and 
in many to only eight, it must be obvious from this, that it would 
be quite impossible to prove the presence of nitric acid in the 
waters of rivers or of springs. 

Under the tropics, where thunder-storms are much more fre- 
quent than with us, we might suppose that the quantity of nitric 

*■ Payen found in 10,000 parts of this water: — 

Carbonate of lime .... 6"80 

" magnesia .... 1*42 

" potash ... - 2-96 

Sulphate of potash - - - - 1-20 

Chloride of potassium - - - - 1-09 

t Re°;n« It found in 22 lbs. of water of the Nile : — ■ 

Carbonate of lime .... 5-30 

" magnesia .... 7'43 

Peroxide of iron .... - 0-53 

Chloride of sodium .... 4-77 

Sulphate of magnesia - - - - 0"53 

Silica 1-06 

Alumina .-.._. 1-59 

Extractive matter .... 0-53 

Carbonic acid - - . . ■ 12'19 

33-93 Gramme* 



DOES NOT YIELD NITROGEN TO PLANTS. 221 

acid in rain-water would be appreciably greater. But the known 
examinations of the spring and river waters of those regions ; 
for example, of the waters of Paipa, near Tunga, of the water of 
the Rio Vinagre. and of the hot mineral sprinj^s of the Cordilleras, 
the analyses of which were instituted by Boussingault, in South 
America, without the presence of nitrates being detected, show 
that there is no foundation for the opinion that a sensibly greater 
quantity of nitric acid is generated in those regions, by the action 
of lightning, than in the temperate zones. 

It follows, from the preceding observations, that nitric acid, or 
its salts, are not destined by nature to yield nitrogen to plants. 
If it were actually the case that nitric acid did yield to plants 
their nitrogen, we must assunie that this source was accessible to 
all plants without distinction. But it is completely excluded 
from marine plants ; and even in the case of the terrestrial plants 
of the temperate and cold zones, the rare occurrence of thunder- 
storms would prevent us from considering that any appreciable 
quantity of their nitrogen could arise from nitric acid generated 
by the action of lightning on the constituents of air. 

But, even on the assumption that nitric acid does take a de- 
cided part in vegetable life, ammonia still remains as the ultiaiate 
source of the nitrogen of plants ; foi", as far as oar knowledge 
at present extends, all the nitric acid on the surface of the earth 
is formed by the eremacausis of ammonia, and it is not impro- 
bable that the nitric acid, which occurs in the rain of thunder- 
storms, may be dependent on the presence of the same body. 

Although we thus trace back the action of all animal and 
other substances containing nitrogen, to the only compound which 
furnishes this element to all plants, in a state of nature, we do 
not of course mean to exclude the application of these other 
matters to the purposes of agriculture. When we know that 
woollen rags, horn, and hair, in the progress of decay, offer a 
slow but continued supply of ammonia, it follows, that we may 
use them wherever their price, in comparison with the advantage 
anticipated, does not exclude their application. 

The same reasoning holds good in the case of nitrates. In 
these, nitrogen exists in another form than that of ammonia. 
Nitric acid, or rather nitrous acid, is, in its chemical relations, 



222 IS NITRIC ACID FOOD FOR PLANTS ? 

exactly opposed to ammonia ; but we see, that in the organism 
of plants, carbonic acid and water suffer decomposition, although 
their constituents are united by a much greater power. We 
have considered sulphuric acid as a source of sulphur. Why, 
then, should not nitric acid suffer a similar decomposition by the 
same causes ; why should not its nitrogen, like the carbon or 
sulphur, become a component part of a plant ? 

By strewing nitrate of soda over fields, a greater crop has been 
obtained, particularly on grass land. Upon corn-fields and on 
roots, it has had less influence. 

It is not yet decided to what constituent of the salt its favorable 
influence is due. 

When the crops of hay and straw obtained with this manure 
by Mr. Gray, of Dilston, and Mr. Hyett (Journal of the Royal 
Agricultural Society), are expressed with regard to their quantity 
of nitrogen, the singular result is obtained, that the amount of 
nitrogen in these crops amounts to double the quantity of that 
contained in the nitrate used as manure ! 

Now, when it is remembered that the crop of many meadows 
is rendered a half, twice, or even three times greater, by ma- 
nuring with burnt bones or with wood ashes — with matters, 
therefore, containing no nitrogen, it still remains doubtful 
whether the action of nitrate of soda should be ascribed to its 
nitric acid. 

A number of plants, such as Borago officinalis, Mesembryan- 
themum crystallinuvi, Apium graveolens, the sun-flower, and to- 
bacco, contain dissolved in their juices considerable quantities of 
nitre, which does not exist in other plants growing on the same 
soil. The presence of a nitrate in plants permits only one con- 
clusion — that the nitrogen of nitric acid is not employed in their 
organism for the formation of compounds containing that element, 
because, if it were, at a certain period of the life of the plant, it 
would disappear on account o'' this conversion. 

Whatever be the case in this respect, nitrates are manures, 
which do not replace those constituents of the soil which are re- 
moved in the crops. Hence, although either by means of their 
Ecid, or of their alkalies, the ; rowth of plants may be increased 
for one or two years, this very increase must cause an earlier 



NITROGEN OF TLE AIR IN VEGETATION. 223 

period of exhaustion and poverty to the soil. A proper and 
lasting advantage cannot be expected from the use of nitrates. 



DOES THE NITROGEN OF THE AIR TAKE PART IN VE- 
GETATION? 

Priestley and Ingenhouss assumed that plants possess the 
power of assimilating the nitrogen of the air. The former states 
that a specimen of Epilobium hirsutiim kept under a glass globe 
of ten inches in height, and of one inch in width, absorbed within 
a month -f- of the air contained in it. 

These experiments have been repeated by Saussure with every 
care (Recherches, p. 189), both in pure nitrogen and in atmo- 
spheric air, exactly according to the method described by Priest- 
ley, but the results were quite the reverse. Saussure observes, 
" I have continued the experiments for a long time, but I never 
could detect a diminution of the nitrogen. The same was the 
case with all kinds of plants which I submitted to the same expe- 
riment. Plants, therefore, do not sensibly diminish the bulk of 
the air ; and these experiments are confirmed by those of Wood- 
house and Sennebier." 

Hence, we have not any direct proof for the opinion, that the 
nitrogen of the air is converted into a component part of a plant 
by its vital processes. In the present state of our knowledge, 
ndirect proofs are equally wanting. 

Many writers on agriculture cite, as decisive proofs of the 
assimilation of the nitrogen of the air by plants, the experiments 
of Boussingault, but their interpretation in favor of this view is 
not supported by facts. This distinguished philosopher instituted 
a number of experiments in order to decide the question regard- 
ing the origin of nitrogen in plants, and we give the results of 
these experiments in his own words (Ann. de Chimie et de Phy- 
sique, Lxix.) : — 

" I believe that I have proved by numerous experiments, that 
the nitrogen of a rotation of plants is greater and often much 



224 NITROGEN OF THE AIR IN VEGETATION. 

greater than the quantity contained in the manure. This exce^ss 
arises doubtless from the air, and it is more than probable that, 
in this case, a part of the excess of nitrogen is taken up in the 
form of nitrate of ammonia, which M. Liebig has shown to exist 
as a frequent constituent of the rain of thunder-storms. But 
before this can be assumed, it will be necessary to examine the 
action of this salt on vegetation." 

In a later treatise on this subject, Boussingault says (Annalea 
de Chimie et de Physique, 3 Serie, t. i., p. 240) : — 

" When these tables are examined, it follows that the nitrogen 
in the plants obtained amounts to more than that present in the 
manure. I assume, as a general proposition, that this excess 
arises from the air. But in what way and manne^ '^^zis ele- 
ment IS taken up by plants, I AM UNABLE TO STATE. The 

nitrogen may be taken up directly as a gas, or dissolved in water, 
or, what is possible, and as some philosophers (Saussure for ex- 
ample) believe, the air may contain an infinitely small quantity 
of ammonia." 

The experiments of Boussingault are, therefore, proofs that 
the nitrogen of cultivated plants is not obtained from manure 
alone, but that, besides this, they contain an excess which can 
only be derived from the atmosphere. That the nitrogen of wild 
plants must be derived from the air is so obvious, that it requires 
neither proof nor experiments. 

Boussingault had not the slightest intention of making his ex- 
periments the foundation for the opinion that the nitrogen of air 
might be converted into parts of the plant, but only employed 
them as proofs that the nitrogen of cultivated plants is derived 
from the atmosphere. 



GIANT SEA-WEED. 235 



GIANT SEA- WEED. 

(From Darwin's Journal of the Voyage of the Beagle, pp. 303, 304.) 

" There is one marine production, which from its importance is 
worthy of a particular history. It is the kelp or Fucus giganteus 
of Solander. This plant grows on every rock from low-water 
mark to a great depth, both on the outer coast and within the 
channels. I believe, during the voyage of the Adventure and 
the Beagle, not one rock near the surface was discovered, which 
was not buoyed by this floating weed. The good service it thus 
affords to vessels navigating near the stormy land is evident, and 
it certainly has saved many a one from being wrecked. I 
know few things more surpri.sing than to see this plant growing 
and flourishing amidst ♦^..ose great breakers of the Western 
Ocean, which no mass of rock, let it be ever so hard, can long 
resist. The stem is round, slimy, and smooth, and seldom has a 
diameter of so much as an inch. A few taken together are 
sufficiently strong to support the weight of the large loose 
.stones to which, in the inland channels, they grow attached ; 
and some of these stones are so heavy, that, when drawn to the 
surface, they can scarcely be lifted into a boat by one person. 

" Captain Cook, in his second voyage, says, that at Kerguelen 
Land, ' some of this weed is of a most enormous length, though 
the stem is not much thicker than a man's thumb. I have 
mentioned, that upon some of the shoals on which it grows, we 
did not strike ground with a line of twenty-four fathoms. The 
depth of water, therefore, must have been greater. And as 
this weed does not grow in a perpendicular direction, but 
makes a very acute angle with the bottom, and much of it 
afterwards spreads many fathoms on the surface of the sea, I am 
well warranted to say that some of it grows to the length of 
sixty fathoms and upwards.' Certainly, at the Falkland Islands, 
and about Terra del Fuego, extensive beds frequently spring up 
from ten and fifteen fathom water. I do not suppose the stem 
of any other plant attains so great a length as 360 feet, as slated 
11* 



22G GIANT SEA-WEED. 



by Captain Cook. The geographical range is very consider, 
able ; it is found from the extreme southern islets near Cape 
Horn, as far north, on the eastei'n coast (according to informa- 
tion given me by Mr. Stokes) as lat. 43° — and on the western it 
was tolerably abundant, but far from luxuriant, at Chiloe, in 
lat. 42°. It may possibly extend a little further northward, but 
is soon succeeded by different species. We thus have a range 
of 15° in latitude ; and as Cook, who must have been well ac- 
quainted with the species, found it at Kerguelen Land, no less 
than 140° in longitude. 

" The number of living creatures, of all orders, whose 
existence intimately depends on that of the kelp, is wonderful. 
A great volume might be written, describing the inhabitants of 
one of these beds of sea-weeds. Almost every leaf, excepting 
those that float on the surface, is so thickly incrusted with coral- 
lines as to be of a white color. We find exquisitely delicate 
structures, some inhabited by simple hydro-like polypi, others by 
more organized kinds, and beautiful compound Ascidise. On the 
flat surfaces of the leaves, various patelliform shells, Trochi, un- 
covei'ed molluscs, and some bivalves are attached. Innumerable 
Crustacea frequent every part of the plant. On shaking the 
great entangled roots, a pile of small fish, shells, cuttle-fish, 
crabs of all orders, sea-eggs, star-fish, beautiful Holuthuriae 
(some taking the external form of the nudi-branch molluscs), 
Planarise, and crawling nereidous animals, of a multitude of 
forms, all fall out together. 

" I can only compare these great aquatic forests of the 
southern atmosphere with the terrestrial ones in the inter- 
tropical regions. Yet, if the latter should be destroyed in any 
country, I do not believe nearly so many species of animals 
would perish, as, under similar circumstances, would happen 
with the kelp. Amidst the leaves of this plant, numerous 
species of fish live, which nowhere else would find food or 
shelter ; with their destruction, the many cormorants, divers, 
and other fishing birds, the otters, seals, and porpoises, would 
soon perish also ; and lastly the Fuegian savage, the miserable 
lord of this miserable land, would redouble his cannibal feast, 
decrease in numbers, and perhaps cease to exist." 



APPENDIX. 



EXPERIMENTS OF WIEGMANN AND POLSTORF 



The composition of the artificial soil 


used in the 


experiments of Wieg 


mann and Polstorf, on the organic ingredients of Plants, was as follows 


(Preischrift, p. 9) : — 






Qua^zy sand 




861-26 


Sulphate of potash 




0-34 


Chloride of sodium 


, 


013 


Gypsum (anhydrous) 




1-25 


Chalk (elutriated) 




. 1000 


Carbonate of magnesia . 




500 


Peroxide of manganese 




2-50 


Peroxide of iron 




1000 


Hydrated alumina 


. 


. 1500 


Phosphate of lime 




15-60 


Acid of peat with potash* , 




3-41 


" " soda . 




2-22 


" " ammonia 


, , 


. 10-29 


lime 




3-07 


" " magnesia 


. 


1-97 


" " peroxide 


of iron 


3-32 


" " alumina 




4-64 


Insoluble acid of peat . 


• 


5000 



* This salt was made by boiling common peat with weak potash ley, and 
precipitating, by means of sulphuric acid, the dark-colored solution. This 
precipitate i.'' that termed Torfsaeure (acid of peat), in the above analysis. 
The salts of this acid, referred to in the analysis, were obtained by dissolv- 
ing this acid in potash, soda, or ammonia, and by evapoiating the solutions ; 
the salts of magnesia, lime, peroxide of iron, and alumina, were obtained 
by saturating this solution with their respective bases, by which means 
double decomposition was effected. Humus is the substance remaining bj' 
the decay of animal and of vegetable matters, which are seldom absent from 
a soil. This was replaced by the acid of peat in the experiments of Wieg- 
mann and Polstorf. When the acid of peat is boiled A)r some time with 
water, it passes into an insoluble modification denoted above as insoluble 
acid of peat. 



228 APPENDIX. 



The following experiments were instituted in pure sand, and in the 
artificial soil : — 

VICIA SATIVA. 
A. — In Pure Sand. 

The vetches attained by the 4th of July a height of ten inches, and 
seemed disposed to put out blossoms. On the 6th of the same month, 
the blossoms unfolded; and on the 11th they formed small pods, which, 
however, did not contain seeds, and withered away by the 15th. Simi- 
lar plants, which had already begun to have yellow leaves below, were 
drawn with their roots out of the sand, the roots washed with distilled 
water, and then dried and incinerated. 

B. — In Artificial Soil. 
The plants reached the height of eighteen inches by the middle of 
June, so that it became necessary to support them wilh sticks ; they 
blossomed luxuriantly on the 16th of June ; and about the 26th put out 
many healthy pods, which contained on the 8th of August ripe seeds, 
capable of germinating. Similar plants to the above were taken with 
their roots from the soil ; they were then washed and incinerated. 

HORDEUM VULGARE. 
A. — In Pure Sand. 
The barley reached on the 26th of June, when it blossomed imperfectly 
a height of 1} foot, but it did not produce seed ; and, in the month of 
July, the points of the leaves became yellow ; on which account, on the 
1st of August, we removed the plants from the soil, and treated them as 
before. 

B. — In Artificial Soil. 

The barley, by the 25th of June, had reached a height of 2i feet, by 
which time it had blossomed perfectly ; and yielded, on the ] 0th of 
August, ripe and perfect seeds ; upon which the plants, together with 
their roots, were taken from the soil, and treated as formerly. 

AVENA SATIVA. 
A. — In Pure Sand. 
The oats, on the 30th of June, were 1 k foot in height, but had blos- 
somed very imperfectly ; they did not produce fruit ; and, in the course 
of July, the points of their leaves became yellow, as in the case of the 
aarley ; on which account the stalks were removed from the soil on the 
^8t of August, and treated as formerly. 

B. — In Artificial Soil. 
f\ie oats reache4 2 s feet on the 28th of June, having blossomed per 



APPENDIX. 229 



fectly. By the 16th of August they nad produced ripe and perfect 
seeds ; the stalks and roots were, therefore, removed from the soil, and 
treated as above. 

POLYGONUM FAGOPYRUM. 
A. — In Pure Sand. 
The buck-wheat, on the 8th of May, seemed to flourish the best of all 
the plants grown on pure sand. By the end of June, it had reached a 
height of I5 foot, and branched out considerably. On the 28th of June, 
it began to blossom, and continued to blossom till September, without 
producing seeds. It would certainly have continued to blossom still 
longer, had we not removed it from the soil on the 4th of September, as 
it lost too many leaves : it was treated as before. 

B. — In Artijicial Soil. 
The buck-wheat grew very quickly in this soil, and reached a height 
of 2i feet. It branched out so strongly, that it was necessary to support 
it with a stick; it began to blossom on the I5th of June, and produced 
perfect seeds, the greater number of which were ripe on the 12th of 
August. On the 4th of September, it was taken from the soil along 
with the roots, and treated as before, on account of losing too many 
leaves from below ; although it was partly still in blossom, and with 
unripe fruit. 

NICOTIANA TABACUM. 
A. — In Pure Sand. 
The tobacco-plant sown on the 10th of May did not appear till the 2d 
of June, although it then grew in the normal manner ; when the plants 
had obtained their second pair of leaves I removed the superfluous 
plants, leaving only the five strongest specimens. These continued to 
grow very slowly till the occurrence of frost in October, and obtained 
only a height of five inches, without forming a stem. They were 
removed along with their roots from the sand on the 21st October, and 
treated as the above. 

B. — In Artijicial Soil. 
The tobacco sown on the 10th of May came up on the 22d of the 
same month, and grew luxuriantly. When the plants obtained the 
second pair of leaves, I withdrew the superfluous plants, and allowed 
only the three strongest to remain. These obtained stems of above 
three feet in height, with many leaves ; on the 25th of July they began 
to blossom ; on the 10th of August, they put forth seeds ; and, on tlm 



i30 



APPENDIX. 



8th of September, ripe seed capsules, with completely ripe seeds, were 
obtained. On the 27th of October, the plants were removed from the 
soil, and treated as above. 

TRIFOLIUM PRATENSE. 
A. — In Pure Sand. 
The clover, which appeared on the 5th of May, grew at first pretty 
luxuriantly, but reached a height of only 3s inches by the I5th of Octo- 
ber, when its leaves became suddenly brown, in consequence of which I 
removed it from the soil, and treated it as above. 

B. — In Artificial Soil. 
The clover reached a height of ten inches by the I5th of October ; it 
was bushy, and its color was dark green. It was taken from the soil, in 
order to compare it with the former experiments, and was treated in the 
same way. 

CONSTITUENTS OF THE ASHES OF THE SEED. 

100 parts of dry seeds yield — 





Soluble In 


Soluble in 




Ashes in 




water. 


muriatic acid. 


Silica. 


JOO parts. 


Vicia faba . 


. l-.56^ 


0-563 


0-442 


= 2-567 


Hordeum vulgare 


. 0-746 


0-.563 


1-1-23 


^ 2 432 


Avena sativa 


. 465 


277 


2122 


= 2-864 


Polygonum fagopyrum 


. 0-823 


0-547 


0-152 


= 1-5-22 


TrifoUum pratense . 


. 1-218 


3-1S7 


0-2S2 


= 4-6S7 



CONSTITUENTS OF THE ASHES OF THE PLANTS GROWN IN PURE SAND 
AND IN THE ARTIFICIAL SOIL. 

Insoluble in water 
Soluble in Soluble in and muriatic acid 

water. muriatic acid. (Silica). Ashes 



Vicia sativa, 
15 grms. plants, 
dried in air . . 

Hordeum vul- 
gare, 12-5 grms. 
plants . . . 

Avena sativa, 
13 grms. plants, 

Polygonum 
fagopyrum . 



Nicotiana 
tabacum . . . 

TrifoUum 
pratense, 1 1'5 
grammes plants 



In sand . . OSIG 
In artificial soil 0-693 



Sand 
Soil 



0-123 
0-167 

0216 
0-2-25 



Sand 
Soil 

Sand (12 U-ose 
grms. plants) ) 
Soil (1-2-7 gr.jQ.^^g 
plants) . . ) 
Sand (4 grms. ) „.., 
plants) . . 5 " - 

plants) . . ) 



'223 



Sand 
Soil 



0-522 
Ofijy 



375 
0-821 

0-195 
0-226 

024 
0-030 

0-094 

0-226 

0-252 

2 "228 

0350 
943 



0-135 = 1026 
0-320 = 1-834 



0-.355 
0-4S7 

0-3.54 
0-461 

0-045 

0-133 

0-031 

0-549 

0-091 
0-082 



0-673 
SSO 

0-594 
0-746 

0-225 

0-507 

0-506 

3-9-23 

0-963 
1-8S4 



APPENDIX 



331 



The preceding numbers express the unequal weight of mineral nutritive 
substances taken up from the sand and artificial soil by equal weights 
of the different plants mentioned. The absolute and not the relative 
weight of the component parts of the ashes is given. For example, tlie 
five tobacco plants grown in sand gave 0-506 gr. in ashes, whilst the 
three which grew in the artificial soil gave 3-923 ; five would, thereforej 
have given 6-525 gr. The proportion of the mineral ingredients taken 
up by five tobacco plants from the sand, and that taken up from the arti- 
ficial soil by an equal number of plants, is as 10 : 120. In an equal 
space of time, those which grew in the artificial soil absorbed nearly 
thirteen times more of inorganic ingredients than those in the sand, and 
the whole development of the plant was exactly in proportion to the 
supply of food. Wiegmann and Polstorf subtracted the ashes of the 
seed used from the numbers in the last line, which show the amount of 
ashes in a given weight of the grown plant ; but this has caused a small 
error in the numbers, as all the plants grown in the sand were reduced 
to ashes, and a corresponding amount only of those grown in the arti- 
ficial soil. The weight of the seed of every plant grown was 3 grammes 
if we except the tobacco, which was not weighed. 

TABLE 

thawing the Amount of Moisture in the Vegetable Substances analysed 
in the Experiments of Boussingault. 





Subst. dried 
at 110° C. 


Water. 




Subst. dried 
at 110° C 


Water. 


Wheat. . . . 

Rye 

Oats . . . . 
Wheat straw . 
Rye straw . . 
Oat straw . . 
Potatoes . . . 


0-855 
0-834 
0-792 
0-740 
0-813 
0713 
0-241 


0-145 
0166 
0-208 
0-260 
0-187 
0-287 
0-759 


Beet 

Turnips .... 
Helianthus tub. . 
Peas ... 
Pea straw . 
Clover stalk . . 
Stalk of Hel. tub. 


0122 
0075 
0-208 
0-914 
0-882 
0-790 
0-871 


0-878 
0-925 
0-792 
0-086 
0-118 
0-210 
0-129 



COMPOSITION OF MANURE DRIED IN VACUO AT 110° C 





Carbon. 


Hydrogen. 


Oxygen. 


Nitrogen. 


Salts & Earths. 


I. 


32-4 


38 


25-8 


1-7 


36-3 


II. 


32-5 


41 


26-0 


1-7 


357 


III. 


38-7 


45 


28-7 


1-7 


26-4 


IV. 


36-4 


40 


19-1 


2-4 


381 


V. 


40-0 


43 


27-6 


2-4 


25-7 


VI. 


345 


43 


27-7 


20 


315 


Mean. 


35-8 


4-2 


25-8 


20 


322 



232 



APPENDIX. 



These results show that the quantity of this manure necessary for one 
hectare of land (4 Hessian acres) during five years contains ; — 



Carbon 

Hydrogen 

Oxygen 

Nitrogen 

Salts and earths 



Kilogrammes. 
3637-6 

426-8 
25-21-5 

203-2 
3271-9 



COMPOSITION OF THE PRODUCE OF THE LAND DRIED IN 
VACUO AT 110° C. 









With the Ashes. 


Without the Ashes. | 




e 




B 


a 




c 


B 


b' 


= 




.M 


o 


61 




.a 


1 


£ 


S) 


o 
























o 


a 


o 


^ 




O 


IS 


o 


2 


A^fheat 


461 


5-8 


43-4 


2-3 


2-4 


47-2 


60 


44-4 


2-4 


Rye .... 






46-2 


5-6 


44-2 


17 


23 


473 


5-7 


45-3 


1-7 


Outs .... 






50-7 


6-4 


36-7 


2-2 


40 


529 


66 


38-2 


2-3 


Wheat straw . 






48-4 


53 


38-9 


0-4 


70 


52 1 


57 


41-8 


0-4 


Rye straw . 






49-9 


5-6 


40-6 


0-3 


3-6 


51-8 


5-8 


421 


0-3 


O it straw . 






501 


54 


390 


0-4 


51 


52-8 


5-7 


411 


0-4 


Potatoes . . 






440 


5-8 


44-7 


1-5 


40 


45-9 


61 


46-4 


1-6 


Beet . . . 






42-8 


5-8 


43-4 


1-7 


6-3 


45-7 


6-2 


46-3 


1-8 


Turnips . . 






42-9 


55 


42-3 


1-7 


7-6 


46-3 


60 


45-9 


1-8 


Helianthus tul 


. 




43-3 


5-8 


433 


1-6 


60 


460 


6-2 


461 


1-7 


Yellow peas 






46-5 


6-2 


400 


42 


31 


480 


6-4 


413 


4-3 


Pea straw . 






45-8 


50 


35-6 


23 


11-3 


51-5 


5-6 


40-3 


2-6 


Red clover haj 






47-4 


50 


37-8 


21 


7-7 


51-3 


5-4 


411 


2-2 


Stalk of Hel. tub 




45-7 


5-4 


45-7 


0-4 


2-8 


470 


5-6 


470 


04 



ROTATION. 







Produce 


Dry 










Salts 


Year. 


Substances. 


of a 
Hectare. 


Produce 


Carbon. 


Hydrog. 


Oxygen. 


Nittog. 


and 
Earths. 






Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kiloer. 


Kilojir. 


1 


Potatoes . . 


12800 


3085 


1357-4 


178 .» 


1379.0 


46-3 


123-4 


2 


Wheat. . . 


1343 


1148 


529-3 


66-ti 


498-2 


26-4 


27 5 




Wheat straw 


3052 


2258 


1093-0 


119-7 


878-2 


90 


158-1 


3 


Clover (hay) 


5100 


4029 


1909-7 


201-5 


1523-0 


84-6 


310-2 


4 


Wheat. . . 


1059 


1418 


653-8 


82-2 


615-4 


32-6 


.■MO 




Wheat straw 


3770 


2790 


1350-4 


147-8 


1085-3 


11-2 


195-3 




Turnips . . 


9550 


716 


307-2 


39-3 


302-9 


12-2 


.54-1 


S 


Oats . . . 


1344 


1064 


539-5 


68-0 


390-5 


23-3 


42-6 




Oat straw 
Total . . 


1800 


1-283 


642-8 


69-3 


500-4 


51 


65-4 


40-U8 


17791 


8383-1 


973-3 


7172-9 


250-7 


1010-9! 


Manure used . . . 


4908G 


10161 


3637-6 


426-8 


2621-5 


203-2 


3271-9 


Differ 


ence .... 




+';630 


+4745-5 


+546-5 


+4551-4 


+47-5 


—22610 



APPENDIX. 



i-S3 



2. ROTATION. 







Produce 


Dry 










Salts 


Year. 


Substances. 


of a 
Hectire. 


Produce 


Carbon. 


Hydrog. 


Oxygen. 


Nitrog. 


and 

Earths. 






Ki'ogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


1 


Beet. . . . 


26000 


3172 


1357-7 


184-0 


1376-7 


539 


199-a 


2 


Wheat . . . 


1185 


1013 


467-0 


58-8 


439-0 


233 


24-3 




Wheal straw 


2693 


1993 


984-0 


105-6 


775-3 


8-0 


1395 


3 


Clover . . . 


5100 


4029 


1909-7 


201-5 


15230 


84-6 


3102 


4 


Wheat . . . 


1659 


1418 


653-8 


82-2 


615-4 


32-6 


34-0 




Wheat straw 


3770 


2790 


1350-4 


147-8 


10853 


11-2 


1953 




Turnips . . 


9550 


716 


307-2 


39-3 


302-9 


12-2 


54-4 


5 


Ojts . . . 


1344 


1064 


539-5 


680 


390-5 


233 


426 




Oat straw 
Total . . 


1800 


1283 


642-8 


69-3 


500-4 


51 


654 


53101 


17478 


8192-1 


956-5 


7009-1 


254-2 


1065-5. 


Manure used . . . 


49086 


10161 


3637-6 


426-8 


2G21-5 


2032 


32719 
—2206-4 


Diffen 


3nce .... 




+7317 


+4554-5 


+529-7 


+4387-6 


+51-0 



3. ROTATION. 







Produce 


Dry 










Salts 


Year. 


Substances. 


of a 
Hectare. 


Produce. 


Carbon. 


Hydrog. 


Oxygen. 


Nitrog. 


and 
Earths. 






Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


Kilogr. 


1 


Potatoes . 


12800 


3085 


1357-4 


178-9 


1379-0 


46-3 


123-4 


2 


Wheat . . 


1343 


1148 


529-3 


66-6 


498-2 


26-4 


27-5 




Wh't straw 


3052 


2258 


10930 


119-7 


878-2 


9-0 


158-1 


3 


Clover stalk 


5100 


4029 


1909-7 


201-5 


1523-0 


84-6 


310-2 


4 


Wheat . . 


16.59 


1418 


653-8 


82-2 


615-4 


3-2-6 


34-0 




Wh't straw 


3770 


2790 


1350-4 


147-8 


1085-3 


11-2 


195-3 




Turnips 


9550 


716 


307-2 


39-3 


302-9 


122 


54-4 


5 


Peas . . . 


1092 


998 


464-1 


61-9 


399-2 


41-9 


30-9 




Pea straw . 


2790 


2461 


1127-3 


1230 


876-1 


56-6 


278-1 


6 


Rye . . . 


1679 


1394 


644-0 


78-1 


6161 


23-7 


32-1 




Eye straw 
Total . 


3731 


3033 


1513-5 


169-8 


1231-4 


9-1 


109-2 


46566 


23330 


10949-7 


1268-8 


9404-8 


353-6 


13.53-2 


Manure used . . 


58900 


12192 


43(j4-2 


512-2 


3145-5 


243-8 


3925-8 


Differ 


snce . . . 




+11138 


+6585-5 


+756-6 


+6259-3 


+109-8 


—2572-6 



4. ROTATION. 



Year. 


Substances. 


Produce 

of a 
Hectare. 


Dry 
Produce 


Carbon. 


Hydrog. 


Oxygen. 


Nitro. 


Salts 

and 

Earths. 


1 
2&3 

Mam 


Manured fallow 
Wheat . . . 
Wheat straw . 

Total . . 
ire used . . . 


Kilogr. 

3318 
7500 


Kilogr. 

2836 
5550 


Kilogr. 

1037-4 
2686-2 


Kilogr. 

164-5 
294-2 


Kilogr. 

1230-O 
2159-0 


Kilogr 

65-2 
222 


Kilogr. 

68-1 

388-5 


10818 
20000 


8386 
4140 


3723-6 
1482-1 


458-7 
173-9 


33898 
1068-1 


87-4 
82-8 


456.6 
13331 


Differ 


ence 


+4246 


+2241-5 


+284-8 +2321-7 


+4-6 


-876-5 



23* 



APPENDIX. 





t:<? 


o» 


« 


M 


^ 


B-o-S 


fcLo 


{^ 






ei 




s 




















M 












e» 


(S 


o 


MO 


(N 




.Stb 


CO 




§8 




m 


t2'- 


CI 


£i 


+ 


d 


t.2 


r- 


t~ 


« 


•>c 


S 


^M 


if. 




^ 
























w^ 










O 




















+ 


e 














M? 


m 


n 


i-l 


e< 


c 


COO 


^ 


s 


s 


§ 




a-o 










>. 










S 










+ 


e 


^,o 

sis 


t^ 


t- 


F-t 


to 


Xi 


^ 


f^ 


00 


« 














^ 


W-* 


'^ 






+ 


a 


Uo 


Oi 


(» 


s 


s 


tS 




















S"^ 


s 


CO 


OS 


$ 


S o! S 
g o g 


6ii 


o 


S 


s 






s 


o 
oo 






Pm K 












•2 


Jd 


: 








g 




ri 


7? 








i2 






^ 








s 


B 
n) 


o 

S 




■a 




X 


s 




s 


s 

e 












1 


s 




• 




J 


>< 


- 






s 


Q 



TABLE 

0/" the Mineral Constituents put on a Hectare of Land, in the Manure 

during Jive years, in Kilogrammes. 







o . 


5"° 






.2 


•a 
c 


t3 


0^ 




I'- 




rh 






c 
be 

1 






2 c 
X 


A-hi^s of the dung . . 


3272 


9S 


C2 


20 


281 


118 


255 


2233 


200 


Composition of the peat 




















ashes 


5000 





270 


15 


300 


30 


115 


3275 


185 


Sum 


8272 


96 


332 


35 


581 


148 


370 


5508 


385 



APPENDIX. 



239 



COMPOSITION OF THE ASHES OF PLANTS GROWN AT 
BECHELBKONN. 



Names of the 


a 


2-0 


h 


6 

a 


.2 










2.S 

CIS 

O 3 




Plants. 


1^ 




p 

f^ 




c 


i 


O 


a! 




'CO 

eg 


sl 


PotHtoes . . . 


134 


71 


11-3 


2-7 


5-4 


1-8 


51-5 


trjce 


56 


0-5 


0-7 


lied beet . . . 


161 


1-6 


60 


52 


4-4 


7-0 


390 


60' 


80 


25 


4-2 


Swedish turnip 


140 


10-9 


61 


2-9 


43 


10.9 


33-7 


41 


6-4 


12 


55 


Jerusalem arti- 
























chokes . . . 


110 


2"2 


10-8 


1-6 


1-8 


2-3 


44-5 


trace 


130 


5-2 


7-6 


Wheat grain . 


00 


10 


47-0 


trace 


15-9 


29 


29-5 


triice 


1-3 


00 


2-4 


Wheat straw . 


00 


10 


31 


0-6 


50 


8-5 


9-2 


0-3 


67-6 


10 


3-7 


Oat grain . . 


1-7 


10 


14-9 


0-5 


7-7 


3-7 


129 


00 


533 


13 


30 


Out straw . . 


32 


41 


30 


4-7 


2-8 


8-3 


24-5 


4-4 


400 


21 


2-9 


Clover. . . . 


250 


2-5 


6-3 


2-6 


6-3 


24-6 


26-6 


05 


5 3 


03 


00 


Peas .... 


0-5 


4-7 


301 


1-1 


11-9 


101 


35-3 


2-5 


1-5 


tr^ce 


2-3 


French beans . 


3-3 


1-3 


26-8 


01 


11-5 


5-8 


491 


00 


10 


trace 


11 


Common beans 


10 


1-6 


34-2 


0-7 


8-6 


51 


452 


00 


0-5 


trace 


31 



(Boussingault, Economie Rurale, p. 327.) 



TABLE OF THE MINERAL CONSTITUENTS, OR ASHES, GIVEN 
TO A FIELD AND REMOVED FROM IT. 





c.Sg 

c o 
~ 2 c. 


„ 










•a 


-| 




Mean produce on one hec- 


*-• 


o 






2 


B 






tare of land=10,000 


Si 


^•^ 


a 






■*o 






square metres. 


°'m5 


w 


IS 


o5 


5 


o 


a 






S 


(L, 


02 


o 


3 


S 


^ 


m 




Isi i)Ianting: 


















Potatoes 


123-4 


13-9 


8-8 


3-3 


2-2 


6-7 


63-5 


6-9 




In the 2d and 4th years : 


















B 


WheiU grain . . . 


550 


25-8 


0-6 


00 


1-6 


8-8 


16-2 


0-8 


t 


Wheat straw . . . 


390-6 


120 


40 


2-4 


33-2 


19-6 


37-2 


264-0 


f f; 


In the 3d year : 


















O 




310-2 


195 


7-7 


8-1 


76-3 


19-5 


84-1 


16-4 


5 


In the 5th year : 




Out grain .... 


42-6 


6-4 


0-4 


0-2 


1-6 


33 


55 


22-7 


^ 


Oat straw .... 


65-4 


1-9 


2-7 


30 


5-4 


1-8 


18-9 


26-2 




Turnips (half crop) . 


54-4 


33 


5-9 


1-6 


5-9 


2-3 


20-6 


35 






1010-9 


82-8 


30-1 


18-6 


126-2 


62-0 


246-0 


340-5 


Ashes of the manure* . 


8272-0 


98-0 


332-0 


350 


5810 


148-0 


3700 


5508-0 




Excess above amount / 
of ashes in the crop . ( 


7201-1 


152 


301-9 


16-4 


454-8 


86-0 


124-0 


5167-5 



(Boussingault, Economie Rurale, p. SJi, n. 336.) 



Consisting of dung and peat ashes, the ashes of -which bore to each othei 
the relation expressed in the following table 



236 



APPENDIX. 



TABLE 

Of the Mineral Constituents added to and removed from the Soil in tfA 
Cultivation of Helianthus tuberosus. (Topinambour.) 



.. 


— 2 
1? 


o 

o 


o 


a 
o 


S 

i3 


.2 

s 
en 


■a 
c 

o 


Silica. 


Ashes of the tubers raised , 
in the 1st and 2d years* | 
Ashes of the dung . . . 
Peat ashes 

Sum of the ashes of the 
manure 

Excess 


6600 

30290 
5000-0 


71-2 

910 



14-6 

57-6 
2700 


10-6 

18-2 
150 


15-2 

260-5 
300-0 


11-8 

109-0 
300 


293-6 

236-2 
115-0 


85-8 

20110 
3275-0 


80390 


910 


3270 


332 


560-5 


1390 


351-3 


5286-0 


73690 


19-8 


3130 


32-6 


545-3 


127-2 


57-7 


52000 



(Boussingault, Economie Rurale, p. 336.) 

* The woody and other parts of the plant were burned on the-spot, and 
thus left to the soil. 



Pay grown in Meadows, watered by the Sauer, near Diirrenbach, in tws 
crops (1841 to 1842) yielded 6 to 6*2 per cent, of ashes of the following 
composition : — 



— 


I. 


n. 


ra. 


Average. 


Carbonic acid 


90 


5-5 





7-3 


Phosphoric acid .... 


5-3 


53 


5-5 


5-4 


Sulphuric acid 


24 


2-9 


— 


2-7 


Chlorine 


2-3 


2-8 


— 


2-6 


Lime 


20-4 


15-4 





17-9 


Magnesia 


6-0 


8-3 





7-2 


Potash 


16-1 


27-3 


— 


21-7 


Soda 


1-2 


23 





1-8 


Silica 


33-7 


29-2 





31-5 


Oxide of Iron • . . . . 


15 


0-6 


0-5 


0-9 


Loss 


2-1 


0-4 




1-0 


100 


100 


100 


1011 



APPENDIX. 



237 



{f the annual produce of hay be estimated on the average at 400 kilo' 
grammes per hectare, then along with it there must be removed in the 



crop, from the same surface. 

Carbonic acid 
Phosphoric acid 
Sulphuric acid 
Chlorine 
Lime 
Magnesia 
Potash and Soda 
Silica . 
Oxide of iron 



244 kilogrammes of ashes, consisting of 
Kilogrammes. 
ITS 
13-2 

66 

6-3 
43-7 
17-6 
57-3 
76-9 

4-6 



244-0 



(Boussingault, Economie Rurale, pp. 339 — 340.) 



COMPOSITION OF A STABLE MANURE. 

ACCORDING TO THE ANALYSIS OF RICHARDSON 

The fresh Manure contained : 

Water ..... 64-96 

Organic matters . . . 24-71 

Ashes ..... 10-33 





100-00 


The Manure dried at 212® contained : — 




Carbon .... 


. 37 40 


Hydrogen .... 
Oxygen .... 
Nitrogen .... 
Ashes 


5-27 
. 25-52 

1-76 
. 3005 



The Asnes contained : 

I. Soluble in Water : 
Pol^ash 

Soda ..... 

Lime .... 

Magnesia .... 

Sulphuric acid 

Chlorine 

Silica .... 

II. Soluble in Hydrochloric acid : 
Silica .... 
Phosphate of lime . 

" magnesia . 

" peroxide of iron 

Carbonate of lime 

" magnesia 

in. Sand (30-99), Charcoal (0-83) 
and Loss (3-14) 



100-00 



3 22 
2-73 
0-34 
0-26 
3-27 
3-15 
0-04 

27-01 
7-11 
2-26 
4-68 
9-34 
1-63 

34-96 



100-00 



ass 



APPENDIX. 







tn 


o 


>* 


PI 


hJ 


k5 


< 


S 


<; 


S 



•^ 



^ 









m 


r- 




^ 


_ 


O — 1 — . to 




^•9nj3Dni 


■<J< r-l 


o. 


(N 






"J< 


oo c. c» e> 




'J8A011 


s°° 




(N 




■^ 


to 


j^ = O M 




O) 




cn 




5 


to 






•AVBflg 












t~ n f, (a 




90JE}0a 


^ 


m 


0< 




CO 


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m 


















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in 
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ou 


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do 


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of magnesia . . 
of iron . . . . 
of alumina . . . 
of manganese . . 




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APPENDIX. 239 



ANALYSIS OF THE ASHES OF THE STRAW OF RYE, BY 
DR. FRESENIUS. 

A. — Ingredients soluble in water and muriatic acid. 

Potash united to silicic acid ' . • . . 6 88 

Sulphate of potash . . . . . . 1-75 

Chloride of potassium ..... 025 

Chloride of sodium ..... 0*56 

Lime united to silicic acid . . . . . 4'19 

Magnesia ....... 0"76 

Phosphate of lime . ■ . . . . . 2'50 

Phosphate of magnesia . . . . . 1"28 

Phosphate of oxide of iron . . . . . 1"57 

Small quantity of phosphate of protox. of manganese. 19'7J 



B. — Residue insoluble in water and muriatic acid. 

Potash united to silicic acid .... 9"21 

Lime united to silicic acid . . . . 3 43 

Magnesia united to silicic acid . . . . . 1*16 

Phosphate of iron . . . . . . 1'63 

Phosphate of protoxide of manganese .... traces 

Silicic acid . . .... 63-89 

Carbonaceoous matter . .... 0'94 



S0-2G 



10000 



Soluble and insoluble logether. 

Potash united to silicic acid ..... 16'09 

Sulphate of potash . . . . . . . 1'75 

Chloride of potassium ...... 0*25 

Chloride of sodium . ..... 056 

Lime united to silicic acid . . , 7"62 

Magnesia .... . . 1'92 

Phosphate of lime ...... 2'50 

Phosphate of magnesia . . . , . 1-28 

Phosphate of oxide of iron .... . 3*20 

Small quantity of phosphate of protoxide of manganese. 

Silicic acid ..... . 63'89 

Carbonaceous matter .... . 094 



10000 



VAC 



APPENDIX. 



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— 1 — 1 ^ to 



u o oo o 

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-paa JO pooAY 



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pan JO IB03J13MO 



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JO pjoajBuo 



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: c S = "H 3 ■£ if 
)Si<aQi-]SOOOO. 



APPENDIX. 



?41 



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ANALYSES OF ASHES BY BERTHIER. 





Fern. 


Wheat 
Straw. 


Share 
Gruss. 


Heath. 


Rhine 
Fern. 


Sulphate of potash . . . . 


0-70 


0-4 


120 


5-0 


3-3 


Chloride of potassium 






trace. 


3-2 


11-4 


1-2 


9-0 


Carbonate of potash 








trace. 




6-8 


16-7 


Potash with silica . 








130 








Silica 








730 


71-5 


50-8 


37-5 


16-5 


Carbonate of lime 








24-8 


96 


6-2 


280 


434 


Sulphate of lime 












14-4 






Phosphate of lime 








10 


2-3 


2-2 


130 


100 


Mai^esia • . . 








05 




30 


1-0 


0-2 


Oxide of iron . . 














1-4 


0-7 


Oxide of manganese 












01 


0-2 










1000 


1000 


1000 


1000 


1000 



12 



•43 



APPENDIX. 



DE SAUSSURE'S INQUIRIES INTO THE ORIGIN OF THE 

MINERAL INGREDIENTS. 





A. 

Granite from 
Mount 
Breven. 


B. 

Stone of the 
La Salle Mount. 


c. 

Limestone. 

of Reculey de 

Thoiry. 




1-74 
13-25 
73-25 

9- 
2-76 


24-36— (Carbonate.) 
4- 
30- 

13- 

27- 

1-64 


9-8 
0-625 

0-625 

0-25 
05 


Alumina 


Oxide of iron and manga- } 

nese J 

Carbonic acid 

Petroleum 





According to De Saussure, the proportion of water, carbon, and ashei 
in the plants, of these three mountains is as follows : 





100 parts fresh 
branches with 
leaves lost by dry- 
ing in the air. ' 


And give, of 


Water. 


Carbon. 


Ashes. 


Pine .... 
Larch. . . . 
Oleander . . 
Bilberry . . . 
Juniper . . . 


51-17 
5807 
59-73 
50-11 
55-19 


48-24 ' 
57-13 i 
52-78 
47-60 
4000 


10-62 
10-16 
9-05 
11-69 
10-63 


B. 

U-ll 
10-39 
9-62 
12-32 
11-46 


A. 

1187 
0-961 
0-654 
1-096 
1081 


B. 

1-128 
0926 
0-339 
1-018 
1082 



100 Ashes contain 



Bilberry. 



Carbonate of potash . 
Sulphate of potash . . 
Chloride of potassium 
Carbonate of lime . . 
Carbonate of magnesia 

Alumina 

Silica 

Oxide of iron and man- 
ganese 



16-38 

40-35 
5-85 
17-54 
13-45 

6-43 



53-70 



14-25 

1-75 



100-00 1 100-00 



360 

4-24 

46-34 
6-77 
14-o6 
1349 

10-52 



99-82 



7-36 ,1 
2-63 ([ 



12-1 
51-19 



11-95 

6-87 



APPENDIX. 



94j 





Oleander. 


Juniper. 






a 


b 


c 


a c 


Carb. sul ph. and chloride of pot. . 

Carbonate of Unie 

Carbonate of magnesia 


10-82 
30-02 

5-00 
28-80 
14-86 

8-40 


1225 
57-00 

13-31 
5-44 
1100 


17-76 
71-54 

5-93 

4-86 


(5-25 
04-25 

0-52 


140 
606 


Silica 


0.xiUe of iron and manganese . . 




97-90 


99-00 


100-09 







100 Parts of the Ashes of the Humus on which those Plants grew, gave— 





Earth of 
Pine. 


Earth of 
Oleander 


E irth of 
Juniper. 


a c 


c 


c 


Salts of potash ....... 

Carbonate of lime 

Carbonate of magnesia .... 


1-16 
0-37 
1400 
60-50 
1600 


4-57 
23-20 

3710 
1310 
16-10 


1-85 
16-65 

43-70 
14-27 
23-83 


13-0 


Silica 


Oxide of iron and manganese . 


9203 94-68 


100-30 





344 APPENDIX. 



ANALYSES OF THE ASHES OF SOME PLANTS, 

BY DE SAUSSURE. 
CHEMICAL INQUIRIES INTO VEGETATION. LEIPZIG, 1805. 



The method of analysis employed by De Saussure consisted of the 
following : 

A. The ashes were treated with water, and the parts soluble in it were 
introduced into the calculations. In the second and following columns. 

B. The residue remaininp^ undissolved in the last operation was dis- 
solved in nitric acid, and evaporated to dryness ; the portion now insolu- 
ble in water was silica. 

C. By precipitating the solution obtained in B, with prussiate of pot- 
ash, the iron and manganese were obtained, the amount of iron supplied 
by the re-agent being subtracted in the calculation. 

D. By a further precipitation of the solution with ammonia, the earthy 
phosphates were obtained (lime and magnesia). 

E. By treating this precipitate with caustic potash, neutralizing it 
with an acid, and precipitating it with ammonia, the earthy phosphates 
mixed with alumina (phosphate) were procured. 

F. By a further precipitation of the liquid D with carbonate of soda, 
and, by continued boiling, the earthy carbonates were obtained. 

G. The difference of the products of these different operations, when 
compared with the total weight of the ashes analysed, expressed the few 
per cent, loss ; and the quantity of salts with alkaline bases which were 
not dissolved by the first treatment with water. 

According to the second mode of procedure, which Saussure considers 
to be the most exact, the ashes, containing alkaline phosphates, were 
chiefly analysed. 

The ashes were dissolved in nitric acid, the lime and magnesia sepa- 
rated as phosphates, the liquor evaporated to dryness, and heated to red- 
ness with the addition of charcoal. 

The residual salts were now saturated with acetic acid, dried and 
treated with alcohol ; the phosphates and sulphates of potash, and chloride 
of potassium, were left behind. 



APPENDIX. 245 



b. The residue was taken up by water, and mixed with acetate of 
•ime : the residue being dried and heated to redness, was treated with 
acetic acid (c), and the portioi not dissolved was estimated as pure 
phosphate of lime, of which it Avas assumed that 100 parts corresponded 
to 129 parts phosphate of potash ; for 8 Ca O + 3 P, Oi gives 3 (Pj O5, 
3K0). 

The solutions a and c, and also that remaining after the precipitation 
with acetate of lime, were evaporated and heated to redness ; the residue 
was weighed, and the chlorine and sulphuric acid estimated, and calcu- 
lated as chloride of potassium and sulphate of potash. By subtracting 
the two latter salts, and also the potash calculated from the phosphate 
of lime, from the weight of the whole residue, the quantity of potash not 
existing as phosphate of potash was obtained. 

Neither of these two methods can be considered accurate in the 
present day. But as all the analyses were executed according to similar 
methods, the results are always of value, in so far as they are, to a cer- 
tain extent, comparable with each other. 



246 



APPENDIX. 



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APPENDIX. 



247 



ANALYSES OF THE ASHES OF PLANTS, 

*Y DE SAUSSTJRE. 









100 Parts Ashes 


contain 






Name of Plant. 














to 

in '3) 


B « o 
«-« S 
.£•-.0 
"s ^ » 

m 


o a 

11 

■a.B 


If 


c 
11 

|i 

a 
O 


03 


Oak leaves 10th May . 


53- 


72-'24 


24- 


0-64 


0-12 


3- 


47- 


" 27th Sept. 


55 




42-5 


18-25 


1-75 


23- 


145 


17- 


" peeled branches . 


4 




58-58 


28-25 


1- 


1225 


0-12 


26- 


" the bark of above . 


60 




29-75 


4-5 


1-75 


63-25 


0-25 


7- 


" wood of same . . 


2 




59-25 


4-5 


2-25 


32- 


£• 


386 


" sap of same . . . 


4 




55-3 


24- 


2- 


11- 


7-5 


32- 


" bark of same . . . 


60 




28-5 


3- 


2- 


66- 


1-5 


7- 


" inner bark of same . 


73 




29-75 


3-75 


1- 


65- 


0-5 


7- 


" extract of the wood 


61 




51- 












Oakwood, mould . . . 


41 




32-5 


10-5 


14- 


10- 


32- 




Aqueous extract of the ) 
mould i 


111 




66- 












Leaves of the Populus ) 
nigra, 26th May . ( 


66- 


51-5 


13- 


1-25 


29- 


5- 


36- 





s *- 

C-3 


100 Parts Ashes contain 




k 


<« Bb 


S si 






Name of Plant. 


•S3 


s ^ 2 


■§.--=' 
II 


.2 c 

ce - 


o 

1^ 




< 

O Xi 

Co 

rt73 




<* 




II 






§1 


Leaves of the Poplar"! 
















(Populxu nigra) 12th > 

Sept J 

Stem of the Poplar . . 


93- 


44- 


7- 


15 


36- 


••5 


26- 


8- 


50-5 


16-75 


1-5 


27- 


3-3 


26- 


Bark of the same . . . 


72- 


292 


53 


1-5 


60- 


4- 


6- 


Leaves of the Hazel-"! 
















nut {Corylut Avel- }► 


61- 


50-7 


323 


15 


22- 


2-5 


26- 


luna), 1st May . J 
















Ditto, 2ai June . . . 


62- 


30- 


19-5 


o. 


331 


4- 


227 


" 20th Sept. . . . 


70- 


44- 


14- 


1-5 


29- 


113 


n- 


Peeled branches . . . 


0- 


28- 


12- 


2- 


36- 


22- 


24-5 


Bark of same .... 
I 


62- 


56-7 


35- 


0-12 


8- 


025 


125 



248 



APPENDIX. 



ANALYSES OF THE ASHES OF PLANTS, 

Bi' DE SAUSSURE. 





m 




100 Parts Ashes contain 




S » 




C.^ 












*l 




s 


J. 










■=1 . 


3 S 




"3 






Name of plant. 




S'S 


O tSi 


J!0 


2^ 
II 


t3 


3 a 






<^ 






6 






Wood of Morns nigra . . 


7. 


41-38 


2-25 


0-2 


56- 


012 


21- 


Soft wood of the same . . 


13- 


47-5 


27-25 


0-2 


24- 


1- 


26- 


Bark of the same .... 


89- 


3013 


8-5 


11 


45- 


15-25 


7- 


Inner part of the bark . . 


88- 


24-38 


16-5 


1- 


43- 


0-12 


10- 


Wood of the white beech, 
















(Jarpinus betulus . . 


6- 


48-63 


23- 


2-25 


26- 


012 


22- 


Sap of same 


7- 


47- 


36- 


1- 


15- 


1- 


18- 


Bark of same 


134- 


34-88 


4-5 


0-12 


59- 


1-5 


45 


Horse chestnut .... 


35- 


9-5 


1 










Leaves of same, 10th May 


72- 


50- 


I Onlj 


• those sf 


ilts whic 


1 are sol 


able in 


From 23d May to 23d July . 


84- 


24- 


f 


water 


were determined. 




From 27th September . . 


86. 


13-5 


J 











Name of plant. 


3 

2 — 

J3 
< 


100 Parts Ashes contain 


Soluble Salts, from 
100 parts of Ashes. 


II 

11 




■0. 


3 

-° 

S3 

Oi 




|i 






Chestnut blossoms . . . 

Sunflower, before blossom- 
ing, 25th June . . . 

Ditto, 23d July .... 

Ditto, with seed .... 

Pine leaves from the Jura, 
2l)th June 

Ditto, from siliceous land . 

Bilberries (chalk soil), 20th 
August 

Bilberries (siliceous soils) 


71- 
141- 

la?- 

69-25 

29- 
29- 

26- 
22- 


50- 

79 67 
79-78 
SKJ-5 

40-13 
34-5 

3639 
41-5 


6-7 

6- 
0-5 

li27 
12- 

18- 
22- 


0-13 

0-12 
4- 

1-6 
55 

18- 
22- 


11-56 
12- 
375 

43-5 
29- 

42- 
22- 


1-5 
1-5 

3.4 
19- 

0-5 
5- 


68- 
61- 
52- 

16- 
15- 

1-7 
24 



APPENDIX. 



248 



1-1 •* 



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250 



APPENDIX. 



C .H x; o ~ c :3 -C o « 
IS 133 r^ B5 ffl B oa E-i M ij 



b OS £<a<b S< 
a; 3 

I I 



o S (u 5" .S c a 

5^5 CO s^"s 






(55 



I I 



•uiuissiuoj 
JO apuonto 



1 1 i:^i Ig I 1 1^ I I I I I M I I 



I I 



■lunipog 
JO apijomo 



1 lo r^ --H o r^ w^ 



(S •*«OOtO >0 00 M « OO 1-1 lO t^ 

n 1 o <b 6» *b o 



•UOJI 

JO iapixdaj 



CO :D lO «3 Tj^ 



to -^ rt ^ lO l^ CO 
tC CO I -^ O l^ LO o< 



JtOtd'ODCOOl 010-. aDt~ 



Co6» I CC'^dtOO-^iinOi^d^-t''- 



•* UO rt to 



•ppv 

oumidiug 



02 to r^ o oi c?^ o ooto to lo -H — X ooi^cooi 
dti^CT iTpeoeo •a>Ai'^d<6tco<j<ijt cod>o« 



•piov 
atjotidsonj 



Ot0Ot;2^O^*-;'-HC0C0^{^t0C0p o:s(?>»fli 



cococococtcococorococ>cof?»cor-(t^ 



rHOM<»0>dS»t^ 



•awjl 



^ t^ f-H CO O C5 tC CO (?» 00 J^ O t^ Ci C^ O i-i '-^ ^ CO •"+ 00 CO l^ CO o o cs 

ao-^cj^t-coctcoi-coocsot^i— ICO ut^asciCioDcooo t^tocoto 

o CD ih d^ 6? o r- lb tc ^ to »h lb Tf a> t-' ih -^ -^oihw cs o tbtS^do 

&*!—( rH CtCOOlCOCO^CO-^ CDC) 



•E!S3u2ei\[ 



O-i^COOr-ITfl-CCCOliOCOCOOOCSOOw ■•-- -, -. — 

tSC0-^CO^^0D05^C0OO05'*w 3 Tfirscyllot^O— 1^ 

•^cotb(X'cb6<03cfccbr-<J<C3T^dD-*o. i^dDdDtbdoA<6:r- 



^ as i^ t^ 00 •* ^ CD oi 



0DC00D(?*Cr»3O liOt^ — (into O OCO'-hCSOCOCO'* 

rHcoc:ipp:cof it^o i'<»>coi-o ito >-icoi^morot^rt 
OTCrj'^'oA.r- Idii^ I rtcbos luo 6»oot-t-i^tb(N 



■Bpog 



O --I ^ Ci o ^ ^ 



Q '^ — ' 
C» i^ t^ 



CO Oi -^ t^ O ' 



<?»»OOCOCOOOU^'H 



"-(COCOCOCOtJl-VCOC^l^COC-ICOCO 



J CO ■^ -* t 

r-lCOC(C 



(?* CS -^ 00 

f- r- C! 



°}ua3 
I9d saqsy 



o: CD o to o 



05 t^ C* UO UO CO cs 
CO I ^H UO !J> 00 00 to 

o> I f- c» (j) d) (N (N 



-C-3 

■5; *; c 

3 5 .r 




4 


s 


si's" 

3 S 

s § 


a 


X 
c 
a 


> 


-,- 


*avesof the white 

turnip . . . . 

sparsette . . . . 

lover, red . . . 






# # * * # ^* # ##*### 



>* 



E '. 

tr u ET •'" 3 

^■5 = = > 

tn &4 Qh ^ 
< * # # 



APPENDIX. 



25 



B 

< 


Engelmann. 

Souchay. 

Engelmann. 

Levi. 

Will and Fresenius. 

Bottinger. 


ai 
J3 

3 
o 
03 


Denninger. 
Kleinschmidt. 

Wrighton. 

L. Hofmann. 
Poleck. 

1 ottinger. 




Bottinger 


"5^ 


Giessen 

Giessen 
Giessen 


a 
o 
5 


Giessen 
Giessen 
Giessen 

■ Giessen 




e 
5 




Red 


o = aj 

O U) 


3-11 

Red 

oxide 

of man- 


be 


oxide 
of man- 
ganese. 

13-15 


•uinissEjoj 
JO apuojqo 


1 1 1 1 1 1 1 1 1 1 1 1 1 1 i 1 


•mnrpog 
JO apuoma 


0-62 
2-31 
3-36 
1-67 
1-17 
0-16 
0-87 




0-02 
0-98 

2-21 
1-49 

1-48 


o 




•UOJI 

JO aptxoiaj 


0-20 
0-24 
2-00 
0-55 
1-46 
0-60 
2-67 




0-38 
1-89 
1-17 
0-82 
1-24 
7-97 
301 
3-51 






■•Eonrs 


19-98 
0-35 
9-13 
2-95 

1-87 
1-09 
1-88 




(j^tot^r^t^to-^-^ 

ipC0OI^C<(NTfO 

ooc*:cx)c»ihort 


s 

CO 




■ppv 

ounqding 


0-80 
3-30 
0-02 

1-62 
1-01 

2-20 




0-78 

1-28 
0-62 
0-75 
5-30 

1-93 


g 


•ppV 
aMondsoqj 


326 
3481 
13-24 
11-24 
19-74 

2-29 
20-81 




2-32 
19-19 
3-33 
1-59 
4-02 
4-85 
45-95 
1-59 


s 




•aiU!7 


OS 00 -'f »A ^ (*» tf^ 




in DC 00 t^ 00 05 00 1;- 

otbr-i^ods-^t^ 
lo -* t~ toc» n 






■•BisauSajvi 


5-10 
8-67 
4-58 
9-01 

11-06 
8-42 

11-64 




3-01 
557 
7-71 
3-19 
8-03 
4-15 
1509 
19-76 


s 




•Bpog 


14-53 
356 
1212 
11-07 

2-04 
9-50 




3-77 

1372 
10-09 
4-53 
5-23 
1-26 
15-99 






•qsBjoj 


7-46 
33-89 
38-97 
42-11 
40-71 
11-80 
22-82 




5-65 
64-64 
21-92 

2-22 
16-14 
35-80 
22-37 

2-79 


»b 




•jiiaa 
jiad saqsy 


10-37 

0-36 
3-19 




0-143 


1 




Plants, or parts of 
Plants. 


um bark 
ca, seeds 
lutum . 
s . . . 
um . . 
r Wood. 
Seeds. 




Wood. 

Seeds. 

Wood. 

Bark. 

Bark. 

Wood. 

Seeds. 

Wood. 


i 




=e 4) O £ 03 




* (iuercus 
Robur . . 

* Ulnius 
canipestris 

* Tilia eu- 
ropoea . . 

* Piiius 
sylvestris . 


.2 

a 



252 



APPENDIX. 



•uinissTijoj 
JO apuomo 



•uinipog 
JO spuomo 



•UOJJ 

JO gpixojaj 



•■BsinS 



•ppv 

ounqding 



•PPV 
ouoqdsoiij 



•aiutl 



•Btsau3Bj\[ 



•JU33 

jad saqsy 



ji ~ =: 



» OJ I ^ 




I I 



H a H 



11 I I III 



-CO c? r^ tjD ^ -^ 



vn-*i-HG->-f-Hoc;GC-rc5r^tci 






OTft^ci 1(0 \n oo^o 



(j^ •^•^■^ 



t^C->OiOOQiOt^tO'-^>OOSOXOaO'H-*'«*C< O uO -^GIC 



uoi>o:>ncOTj"'<tooa:c^oyDc>»oot^«'?-7C->co ©^ 



'*C:C>0'*i-<ift!J^'«J"tCCDCOOC5iO'^QOt^CO«0 W « COt^CO 



ic5S' 



lC0C^rtC0"^^lO»O'^'*r-C^C0r-l t}< i-I r-l 



CiOit^oocccTr-^porot-ooc^Tfj-^t-cscjT*' oo ci oo"-! 



ceo a: t-^ 1-^ CO 



1 1 1; 



01 O* CO O Ci 



UOf-COOSOCOQOr-QOQOKOCOCOi^-HQOi 



liO -^ LO t'- CO "^ -^ 



t^i-HdDcoioKooooC'»©i>JoyDcocoC'i!-Hc:coo -^ ijO f^Sc 



oc CO r~- I o ITS o 



i5& 






* * * * # 




APPENDIX. 



253 





















>. 












p 








o 






s 








< 


§ 

.a 
a 
S 
m 






1 













Si 


dad 

erara 
nd of 
nada 
lica 


S3® 

11 i 


'3 S 


0- 1 1 1 1 e 


■a 
a 




— 




c — 




ti ' ' ' ' e 

i S 


"'SO 


■a -S 





g <0 
































S) bijf^ 






1 1 1 1 1 1 1 


1 


1 


eo 1^ 1 


I 1 


s's^ 


S 1 


1 














fes 


1 


1 


•uinissKjoj 


r-( M 1> ■>»• OO « O 
irj O Sft — 1 — 1 rt< o 


CO 


X 




•lunipog ^ 




1 


JO apijomo 

•UlUlpOg JO 




oo 


« 


JO apjpoi-i. 
















2S!5SSS 


gs 




X 


X 
CO 


sPiJORO 


M 1 1 1 1 1 


1 


1 


SSSS^* 


{-(N 


1 


to 





■iio.ij 








i^xto 

10 S> S» CO 1 










JO apixoiaj 


1 1 / 1 I 1 1 


1 


1 


0660 1 


1 1 


1 








ira ^ •<)< GO Ti" (X> M 
ao S i^ -o o i^ ci 




















en 


•* r-. 3 CO 








'!* 


••Bonis 


O -.S 35 •* t~ O —1 
^ rf -^ -^ ^ G* w^ 






MrtrtOO 


CO 


1 


1 






■^ 
















Si^nrot^Oi m 


s 


^ 












■ppv 














ounqding 


O £- CD C^ t^lO CO 


U5 


■^ 


C) -W ■* X r-l 


if5 rt 


■* 


•* 


o< 


S?2SS3§ S 


lO 


to 








Ui 


S 


•ppv 














auondsoqj 


f X ffl Tl" t^ -^o to 


»» 





(J«i-I rtCOO 


60 


CO 












o 




-3<tOO -H-H 


c: —1 






(N 




oit- o ■» c( t^ >n 


Tt< 


c» 


OS CO -^ f a 


m -( 




X 








A4 




OX -l-V -H 


ctco 


s 


m 


c« 






^ 
















^ 


t~ 




PI 






^ 


•bts3u3ei^ 


ao to si tr- a^ m a 








1 ■:- 


, 




r-i 


zsio 0^ ^mo io 


lO 


10 


totoos = o 


1 


1 




^ 




W ^ r-< 






"^ 












































X 


•Bpog 


-<(Nco i^x ■* e< 


"^ 


&< 


f- Olrf X 1 





L 


" 







■-H OJ X CO C> X IQ 
•H » Tf Ott ^ 00 


















«5 





to 0-1 05 1 


c» --o 






CT. 




^X c= -1= I" to 


in 


X 


oco csro 1 


■tOi 


1 






















•juaa 


























1 <^ 


r^ 






jad saqsy 


1 1 1 1 1 1 1 


1 


1 


jOtO lOCO 


1 ■* 


^ 


1 


I 


o 




>^ 


i 


• • • \a 


5,2 


























tS ■ 

o 3 


S s 






* digitatus 

* vesiculosu 
"* I.odosus 

* serratus 
linaria latif 


'bD.2 





3 



3 


a 


2 2 

^ a 






11 


2 


J 


> 
3 


CL, 


" 1 








.T J£ 






3 




w c 






■snanj ►J 


JW 


0. 





U, 



254 



APPENDIX. 



"3 
< 


■Forchhammer. 

Souchay. 
Wrjghton. 

Riilling. 


It 
^5 


Greenland 

Hoffmans- 

gave. 

Bay of 

Campeachy 

Atlantic 

Ocean 

Kattegat 

Kattegat 
Hoffinans- 
gave 
Kattegat 
Hoffmans- 

gave 
Kattegat 

■ Giessen 

■ Giessen 




1 1 1 1 III 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 


•luniss^oj 
JO apuoino 


3-40 
7-55 
11-88 
7-15 
14-26 
18-49 
14-66 


•uinipog 
JO apiioiMO 


3-81 
4-70 

7-09 

1-98 
0-08 

2-22 

16-61 
9-03 

2-84 


•UOJI 

JO apixoiaj 


3-94 
2-40 
3-19 
1-21 
1-21 
1-61 
3-28 
1-65 
1-65 
1-91 


•Boing 


0-19 

0-48 

5-21 
2-62 
12-78 
1-41 
2-39 
3-29 
6-80 
1-53 
1-65 
2-39 


•ppv 
ouniiding 


§ 5 S g} S S S S SS S ,5gS^§gS§§ 


•piov 
ouoqdsoqj 


<s \ oo ooooo o -^ o -H ih t> i> »^db »o M 


•aiaiT 


110 1-16 

1-09 4-39 
0-68 5-69 

1-98 1-40 

234 1-48 

0-70 1-38 

— 1-05 

2-32 0-69 

0-75 0-51 
17-56 4-11 
8-39 24-96 
6-53 15-65 
506 23-37 
6-14 29-27 
4-56 15-49 
3-67 16-01 
4-79 16-42 
4-94 19-10 
7-70 1 11-48 


•BisauSBivi 


•Bpog 


(nI rto ■if n o s o a\-^a>n 1 1 1 1 i ! 1 


•tlSBJOJ 


3-64 

5-00 
009 

3-83 

3-57 

0-76 

119 

3-43 

1-73 
20-22 
21-69 
43-53 
33-11 
22-86 
36.54 
30-58 
32-39 
25-49 
32-93 


•juao 
jad sa<{sy 


16-22 
15-65 

22-58 

11-62 

18-92 
20-61 
11-23 
9-86 
1710 
13-17 

12-80 
10-89 
6-85 
13-20 
7-32 
9-66 
969 
8-51 
6-90 


o 

H 

1 


Fucus vesiculosus . . 
HaJidrys siliquosa . . 

Sargassum vulgare . . 

Sargassum cocciferum . 

Furcellaria fastigiata . 

Chondras crispus . . . 
Chondrus plicatus . . 
Iridtea edulis .... 
Polysiphonia elongata . 

Delesseria sangninea 

* Ditura Stramoii. Seeds 

* Oonium maculat. . . 

* Digitalis purp. . . . 

* Chelidonium m . . . 

* Agrostemina Gith. . . 

* Centiurea Cyanus. . 

* Anthemis arvensis 

* Matricaria ) 1. 
chatnoniilla ) II. 

* Acorus Calamas . . 



APPENDIX. 



355 



ANALYSES OF ANIMAL EXCREMENTS. 



1000 parts of human faeces left 150 parts of ashes (Berzelius), which 
consist of : — 

Phosphate of lime 1 

Phosphate of magnesia > 100 

A trace of gypsum ..... .J 

Sulphate of soda • ^ 

Sulphate of potash > 8 

Phosphate of soda J 

Carbonate of soda 8 

Silica 16 

Charcoal and loss 18 



150 



Cowdting. 

(Haidlen.) 
Phosphate of lime . . . . 10-9 
Phosphate of magnesia . . . lO'O 
Peroxide of iron . . . . 8'5 

Lime 1-5 

Gypsum 3'1 

Chloride of potassiom, copper . traces. 
Silica . . . . . . 63-7 

Loss ...... I'S 





Horsedung. 




(Jackson ) 


Phosphate of lime 


. 50 


Carbonate of lime 


18-75 


Phosphate of magnesia 


. 36-25 


Silica 


4U 



1000 



According to Berzelius there are contained in — 



1000 parts 
Human 
Urine 

Urea 3010 

Free lactic acid °| 

Lactate of ammonia Il7-lil 

Extract of flesh >i' i* 

Extractive matter ..... .J 

Uric acid ....... 1-00 

Mucus of the bladder 0-32 

Sulphate of potash 3-71 

Sulphate of soda .... . 3-16 

Phosphate of soda 2-94 

Bi phosphate of ammonia 165 

Common salt 4-45 

Sal ammoni-dc 1-50 

Phosphate of magnesia and lime . . . I'OO 

SUica 003 



Water 



100 parts 

solid residue 

of Urine. 

44-39 

85-58 

1-49 

0-48 
5-54 
4-72 
4 39 
2-46 
6-64 
2-23 
1-49 
005 

10000 



1000-00 



S5P 



APPENDIX 



ANALYSES OF URINE BY LEG ANN.* 







In 1000 Parts. 








,„ 




»- J 


■a 










■a 


° ri 


g s 






URINE, 


5 


C3 


u 




■~ s 




.a 2 £ 






« 


£ 








c-a 2 








^ 




.u 


S o 


.M O. 


= t^ 5 


^■-tL 










& 


j-ca 


<'i 


e.'z< 


£-3 




"1 20 years . 


93000 


3000 


1-12 


4-60 


4-42 


0-39 


0-41 


Of a Man 
aged 


22 years . 


928-80 


21-88 


0-97 


2-40 


545 


0-24 


1-64 


J-38 years . 


923-30 


27-80 


121 


3-76 


453 


0-47 


0-93 


86 years . 
J 85 years . 


95300 


8-10 


043 


0-70 


2 92 


1-14 


0-29 




959-50 


13-78 


0-24 


1-63 


293 


0-25 


0-27 


Ofa 


1 
















Woman 


J.28 years . 


95300 


1310 


0-24 


0-17 


2-25 


1-15 


0-46 


aged 


















Ofa Girl 

aged 
Ofa Boy 


1 19 years . 


941-00 


24-59 


0-63 


0-80 


7-85 


2-43 


0-62 


1 8 years . 


948-00 


19-20 


0-23 


380 


3-21 


0-52 


0-85 


aged 


) 3 years . 


96100 


17-30 


024 


— 


~* 


— 





ANALYSES OF URINE BY LEHMANN.t 







■a 




3 


if 
=1 


c 
.5 S 

■a s 
C. 2 


■S 

a 


4 

o 
M 

o 


S .1 


(Quality of Urine. 


'3 


^ 
3 


2 

P 


Id 

5 


-a « o 


S 

1 < 




S 

c 


Ml 






OQ 






3^ 


S OS 


M 

< 


o 


1=1 


Urine in cases of " 


934-002 


65-998 


32-914 


1-073 


13-180 


3-602 


7-289 


3-666 


1-187' 


very strictly re- 
gulated ordi- 


f. 937-682 


62-318 


31-450 


1-021 


14-185 


3-646 


7314 


3-765 


1-132 j 


nary diet . . . , 


932019 


67-981 


32-909 


1-098 


14-859 


3-712 


7-321 


3-989 


1-108 ; 


Urine from ani- 


909-32 


96-68 


53-79 


1-41 


9-36 


5-37 


11-51 


5-52 


3-72 1 


mal food . . . 


933-27 


66-73 


41-65 


1-18 


6-62 


3-46 


7-08 


4-04 


2-70 j 


Urine from vege- 
table food . . 


929-10 


70-90 


38-31 


1-17 


25-70 


3-80 


7-16 


3-54 


1-22 1 


'■941-91 


58-09 


2242 


1-01 


18-49 


3-07 


7-14 


3-68 


1-09 , 


934-92 


65-08 


25 69 


0-89 


82-62 


3-71 


7-23 


3-74 


1-11 1 


Urine from non- 
nitrogenized 
lood . . . . . 


> 953-98 


46-02 


18-92 


0-89 




2-74 


3-25 


3-01 


1 
1-00 ; 


955-11 


34-89 


11-08 


0-54 




1-14 


2-98 


5-48 


0-91 

J 



* Simon, niedicinisciie Chemie, Part ii., pp. 357 and 358. 

t Beitrftge zur physiolojischen und pathologisc hen Cliemie, S.t., von F. Simon, Vol. I. 
p. 190. 



APPENDIX 



'ibl 



URINE OF HERBIVORA. ANALYSES OF VON BIBRA.' 





In 1000 PartSk 1 








c 




















m • 










URINE. 


Extract! 

Matter 
Soluble 

Water 




Salts 

Soluble 

Water 


Salts 
Insolub 
in Wate 


<a 

t5 


53 

EC 


3 
S 




I.] 2ra2 


25-50 


23-40 


18-80 


12-44 


12-60 


005 


885-Of 


Of the Horse > 

II. J 19-25 
















18-26 


4000 


8-36 


123 


006 


912-84 


Of the Pig .11 Ifl 


3-87 


9-09 


0-88 


2-73 


— 


0-05 


98196 


3-99 


8-48 


0-80 


2-97 





0-07 


982-57 


Of the Ox •H'lttl 


1421 


24-42 


1-50 


19-76 


5-55 


007 


912-01 


10-20 1 


25-77 


2-22 


49-21 


12-00 


0-06 


923-11 


OftheGoatjI;! ^^^ 


4-54 


8-50 


0-80 


3-78 


1-25 


0-06 


930-07 


466 1 


8-70 


0-40 


0-76 


0-88 


0-05 


983-99 


Of the Hare I. 3268 


9-58 


23-70 


12-64 


8-54 


— 


— 


912-86 



-aUUfl tIDB8 UI punoj 9J9AV uoji jo SaORJX 



-BDins 



-uinipog 
JO apuojuo 



■T!isau3Biv JO 
aiBqdsoiij 



-anti'i JO 
ajBudsoqj 



•Bpog JO 
aiBqdsotij 




-upog JO 
ajijuoqjBg 



-qy^ojjo 
aiBuoqjcg 



BisauSBH JO 
aiBUoqjBO 



'atuiT JO 
aiBuoqjBO 



oj 



J »3 rf g rt 






D,--! t~ 



— 3 _o 



I I 



I I 



I 1 



1 I 



I s 



(i, o o 



o o 



* Annalen der Chemie und Pharmacie, Vol. liii., p. 



t Ibid. 



258 APPENDIX. 



Horse. 


Cow, 


3100 


18-48 


4-74 


1651 


2009 


1716 


416 


4-74 


10-82 


055 


118 


3-60 


t 


t 


0-74 


1-52 


101 


Spur 


910-76 


92132 



URINE OF HERBIVORA. 

ANALYSED BT BOUSSINQAULT.* 

Pig- 
Urea 4-90 

Hippurate nf potash ...... t 

Laetrile of potash not determined 

Carbonate of magnesia 087 

. of lime ....... Spur 

Sii!ph ite of potash 198 

Phosphate of potash 102 

Chloride of sodium ...... 1-28 

Silica 007 

Water and organic matter not determined . . 979-14 

100000 



GUANO, AFRICAN. 

ANALYSED BY TESCHEMACHER. 

Volatile ammonia and salts, as oxalate, phosphate, and humate, with animal matters 

containing 5 per cent, ammonia 35 

Fixed alkaline salts, as chloride, sulphate and phosphate of potassium ... 11 

Phosphate of lime and magnosid .32 

Water 30 

Earthy matters 2 



GUANO, CHILIAN. 

ANALYSED BY COLQUHOUN. 

Crate of ammonia, ammoniacal salts, and decomposed animal matter . . 17-4 

Phosphate of lime and magnesia, oxalate of lime 48'1 

Fixed alkaline salts 10-8 

Stony matters 1'4 

Moisture 22'3 



100 



{Land., Edinb., and Ditdl. Phil. Mag., 1844, May and June) 



CHILIAN GUANO. 

ANALYSED BV DR. URE. 

Combustible, organic, and volatile matter, containing 2i per cent of ammonia . 22-5 

W;iter 24 

Silica 0-5 

Phosphate of lime 53 

100 



* Annates de Chimie et der Phys., Septerabre, 1845, p. 97. 

t Hippuric acid could not be detected even when the pig with its food (potatoes; had 
arge rations of fresh clover. 
t No phosphate could be found. 



APPENDIX. 



259 



PERUVIAN GUANO. 

ANALYSED BY DR. URE. 

Nitrogenised organic matter, including urate of ammonia . . 50 

Water 11 

Phosphate of lime 25 

Phosphate of ammonia and magnesia, phosphate of ammonia, 

oxalateof ditto, containing 4°9 per cent, of ammonia . 13 

Silica ] 



100 



{Lond., Edinb., and Dubl. Phil. Mag., 1844, May and June.) 



AFRICAN GUANO. 

ANALYSED BY DR. URE. 

Baline and organic matter, containing 10 per cent, of ammonia . . .50 

Water 21-5 

Phosphate of lime and magnesia, also of potash 26 

Silica 1 

Sulphate of potash and chloride of potassium 1-5 

100 

{Land., Edinb., and Dubl. Phil. Mag., 1844, May and June.) 



AFRICAN GUANO. 

ANALYSED BT DR. URB. 

Combustible animal matter 37 

Ammonia, chiefly as phosphate 9"5 

Alkaline and earthy phosphates 18'5 

Alkaline, chiefly potash salts 6'0 

Silica O-o 

Water .... 28-5 

100 



GUANO. 

ANALYSED BY KERSTKN.* 



Combustible matter, of which in No. I. 3-2, in II. 3-2, 
and in III. 6.5 per cent, of humic acid, and of uric 
acid in I. 27 per cent, in the others, traces 

Ammonia 

Phosphate of lime and magnesia 

Phosphate, sulphate, and chloride of potassium and 
sodium 

ttuarey sand . . 

Water . . 



I. 

Peru. 


n. 

Peru. 


III 

Africa. 
Island of 
Ichaboe. 


36-5 

8-6 

20-5 


350 

7-5 
22-5 


3y-5 
95 
175 


6-5 

1-5 

260 


8-2 
20 
250 


7-3 

1-3 

250 



• Journal of Practical Chemistry, Vol. xxxiv., p. 361. 



200 



APPENDIX. 





o 


to 


<b 


6« 




-OUIUIV IBg 


« 

s 


15 


1 




^ 
^ 


•uinipog 
JO apuomo 


! 


1 


1 


6> 


n 


JO a'puomo 


1 1 1 1 1 


•■epog 
JO ajBiBxo 


1 1 1 I 1 


•Binomurv 

JO ajBIBXQ 


o 


00 

s 




i 


1 


•aanq; 

JO 8}BHClS0HJ 


1 1 I 1 1 


•■Giuouiniv 
JO ajBqdsoqj 


m 
n 

CO 


1 


(O 


1 


1 


••epog 
JO DjBqdsoqj 


1 1 1 1 1 


•XISBJOJ 

JO ojBqdsoqj 


1 






s 

■* 




•■Epog 

JO ojuudpig 


i 

an 




?: 


i 




•qsmoj 
JO oiBqdins 


I'll' 


•wjBA\ 


§ 


o 
in 
S 


1 


• o 


s 

I' 




^ 




^ 


a 



APPENDIX. 261 



GUANO. 

ANALTSEE BY DR. J. DAVY 



American Afrlcai 

Guano. Gnana 

Soluble matters, oxalate, phosphate, and chloride of ammonium, 

and animal matters 412 40'2 

Incombustible and insoluble, chiefly phosphate of lime and of 

magnesia 29 282 

Incombustible, soluble, chloride, carbonate and sulphate of pot- 
ash . 2-8 6-4 

Combustible, sparingly soluble, chiefly urate of ammonia . 19 

Expelled by drying ; water and carbonate of ammonia ... 8 25-3 

100 100 

Davy found no Urea and no Oxalic Acid. 

GUANO, AFRICAN. 

ANALYSED BY FRANCIS. 

Volatile salts, as oxalate and carbonate of ammonia, sal ammoniac, and combusti- 
ble organic matter, containing 5'50 per cent, of humic acid, uric acid, and 

extractive matter, and 9'70 per cent, of ammonia 42-53 

Water 2713 

Phosphate of lime and magnesia 2239 

Sand • . . . 0-81 

Alkaline salts, chiefly phosphate, chloride, and a little sulphate of potassium . . 7-08 

100 
{Land., Edin., and JDubl. Phil. Mag., 1844, May and June.) 



ANALYSIS OF A BROWNISH YELLOW GUANO. 

BT OELLACHER.'*' 

Sal ammoniac . . 2'25 

Urate of ammonia . . 12-20 

Oxalate ditto 17-73 

Phosphate ditto .... .... 690 

Carbonate ditto 080 

Humate ditto 1-06 

Phosphate of ammonia and magnesia .... 11-63 

Phosphate of lime 20-16 

Oxalate of ditto 1-30 

Carboniite of ditto 1-65 

Chloride of sodium 0-40 

Sulphate of potash 400 

of soda 4-92 

Waxy matter 0-75 

Sand • 1-68 

Water 4-31 

Undetermined organic matter ... ... 8-26 

100-00 



♦ Fhannac. CentraJblatt., 1844, p. 17 — Buchner, Repertorlum, vol. xxzii., pp. 389— 33Q 



262 



APPENDIX. 



2.— CONSTITUENTS SOLUBLE IN HOT WATER, IN 1000 PARTS. 





Phosphate 
of L^me. 


Phosphate 
of Soda. 


Phosphate 

of Am- 
monia and 
Magnesia. 


Uric Acid. 


Urate of 
Ammonia. 


Organic 
Matter 

11-80 
6-38 
8-60 

1000 
7-56 


I. 

II. 
III. 


1-86 

2-88 

11-37 
1-10 


1-20 (?) 
1-28 (?) 
Spur. 
Spur. 


5-64 
404 

7-84 
Spur. 
1-33 


25-16 


154-18 
25-12 



3.— CONSTITUENTS INSOLUBLE IN WATER, IN 1000 PARTS. 





fc- 


^_ 








































» d 


o 




















» « 


■H 







c 2 




n 




^ 


1= 


1= 


•a 
s 

m 




S 




i 


1 


I. 


197-50 


20-30 


25-60 


15-60 




26-36 


34-56 




0-44 


19200 


19-84 


107-26 


16-48 





20-60 


11-40 


42-42 


J-50 


II. 


62-70 


8-74 


109-58 


7-20 


— 


8-62 


— 


49-74 


4-98 


664-47 


30-56 


— 


20-43 





29-73 


— 


80-60 


2-68 


III. 


131-13 


25-80 


— 


4-20 


1-50 


18-36 


— 


— 


— 



ANALYSES OF ANIMAL EXCREMENTS, 



Guano. 

A sample Guano. Nightingales' 
from Liverpool, from Lima. dung. 

Bartels. Volkel. Braconnot. 

Sal ammoniac 6500 42 02 

Oxalate of ammonia 13-351 106 

Urate of ammonia ... . . 3-244 90 527 with potish 

Phosphate of ammonia 6250 60 08 with potash 

Waxy matter 0600 

Sulphate of potash 4227 55 33 

Sulphate of soda 1119 38 

Phosphate of soda 5-291 

Phosphate of ammonia and magnesia . . 4196 26 0-2 

Common salt 0100 08 

Phosphate of lime 9 940 143 43 

Oxalate of lime 16 360 70 

Alumina ...... .0104 

Residue insoluble in nitric acid . . . 5800 47 
Loss (water, ammonia, undetermined organic 

matter) .... ... 22-718 32 3 377 

100-000 



APPENDIX. 263 



ANALYSES OF THE ASHES OF THE SOLID EXCREMENTS OF 
THE HORSE. 

BT JOHN ROBINSOK ROGERS. 



The fresh excrements consist of— 

Organic matter 19-68 

Inorganic matter or ashes 3-07 

Water . , 77-25 



lOO'UO 



In 100 parts of the ashes there are contained of matter — 

Soluble in water 3-16 

Soluble in hydrochloric acid 22-59 

Insoluble in both ... .... 74-45 

100-00 



COMPOSITION IN 100 PARTS. 



Of the Matter 
soluble in Water 
and in Acid. 
Silica , . .... 6-13 

Potash 24-55 

Soda 000 

Oxide of iron 4-42 

Lime 14-91 

Magnesia. . . . . 10-70 

Oxide of manganese . . . 0*00 

Phosphoric acid . , . 37-54 

Sulphuric acid . . . 1-99 

Chlorine . ... 014 

I'BH ... — 



Of the Residne, 




insc able in Water 


Of the whole 


and Acid. 


Ash together 


81-92 


62-40 


6-71 


11-30 


2-67 


1-98 


005 


117 


106 


4-63 


1-46 


384 


2-87 


213 


111 


10-49 


1-78 


189 


000 


003 


037 


014 



locas loooo loooo 



264 



APPENDIX. 



MARLE. 

ANALYSES BY DR. B. O. F. KROCKEB.* 

The locality of the different kinds is on the left bank of the Rhine, between 
Mayence and Worms. 





I. 


II. 


m. 


IV. 


V. 


VI. 


VII. 


Carbonate of lime. . 
Carbonate of mag- ) 

nesia .... J 

Potash 

Water 

Clay, sand, & oxide ) 

of iron . . . . ) 
Ammonia .... 


12-275 

0-975 

0-087 
2036 

84-52.5 

0-0047 


14-111 

Spuren. 

0-082 
2146 

82-830 

0-0077 


18-808 

1-228 

0092 
2-111 

76-827 

0-0988 


20-246 

3211 

0-091 
1-311 

74-325 

0-0768 


2.5-176 32-143 

2-223 i 1-544 

0-105 I 0-101 
1934 i 1-520 

69-570 64-214 

0-736 0-0955 


36066 

1106 

0-163 
1555 

60-065 

0-0579 



TABLE OF THE AMMONIA CONTAINED IN THE SOIL. 

BY DR. KROCEER.T 











Soils examined. 


Ammonia 
in 100 parts 

of Earth 

dried in the 

Air. 


Specific 
Gravity. 


stratum of solid 

Matter 025 

metre thick, on 

1 hectare, in 

pounds. 


Clay soil, before manuring 


0-170 


2-39 


20314 


Clay soil 


0-163 


2-42 


19723 


Surface soil, at Hohenheim . 


0-156 


2-40 


18730 


Subsoil of the same field 


0104 


2-41 


125;!2 


Clay soil, before manuring 


0149 


2-41 


17953 


Clay soil, before manuring . 


0-147 


2-41 


17713 


Clay ready to be sowed with barlsy 


0-143 


2-44 


17446 


Clay soil, before manuring . 


0-139 


2-41 


16749 


Loamy soil, before manuring . 


0-135 


2-45 


16.^37 


Loamy soil, before manuring 


0-133 


2-45 


16292 


Earth from America, never manured 


0-116 


218 


12644 


Sandy soil, never cultivated 


0096 


2-50 


12000 


Loamy earth, dug out .... 


0-088 


2-5 


11000 


Sandy soil, never cultivated 


0-056 


2-51 


7028 


Nearly pure sand 


0-031 


2-61 


4045 






00988 
00955 
00768 




11952 
11552 
9288 


Marie . .- 




00736 -, 

00579 

00077 


2-42 


8904 

7004 

931 




'■ 


00047 


L 


568 

1 



* Annalen der Chemie und Pharmacie vol. Ivii., p. 369i 
t Ibid., vol. Iviii., 1846. 



PART II. 



THE CIIEMCAL PROCESSES OF FERMENTATION, DECAY, 
AND PUTREFACTION. 



CHAPTER I. 

Chemical Transformations. 



Woody fibre, sugar, gum, and all such organic compounds, 
suffer certain changes when in contact with other bodies — that 
is, they suffer decomposition. 

There are two distinct modes in which these decompositions 
take place in organic chemistry. 

When a substance composed of two compound bodies, crystal- 
lized oxalic acid for example, is brought in contact with concen- 
trated sulphuric acid, a complete decomposition is effected upon 
the application of a gentle heat. Now, crystallized oxalic acid 
is a combination of water with the anhydrous acid ; but concen- 
trated sulphuric acid possesses a much greater affinity for water 
than oxalic acid, so that it attracts all the water of crystallization 
from that substance. In consequence of this abstraction of the 
water, anhydrous oxalic acid is set free ; but, as this acid cannot 
exist in a free state, a division of its constituents necessarily 
ensues, by which carbonic acid and carbonic oxide are produced, 
and evolved in the gaseous form in equal volumes. In this 
example, the decomposition is the consequence of the removal 
of two constituents (the elements of water), which unite with 
the sulphuric acid, and its cause in the superior affinity of the 
acting body (the sulphuric acid) for water. In consequence of 
the removal of the component parts of water, the remaining ele- 
13 



206 CHEMICAL TRANSFORMATIONS. 

ments enter into a new form ; in place of oxalic acid, we have 
its elements in the form of carbonic acid and carbonic oxide. 

This form of decomposition, in which the change is effected by 
the agency of a body which unites with one or more of the con- 
stituents of a compound, is quite analogous to the decomposition 
of inorganic substances. When we bring sulphuric acid and 
nitrate of potash together, nitric acid is separated in consequence 
of the affinity of sulphuric acid for potash j in consequence, 
therefore, of the formation of a new compound (sulphate of 
potash). 

In the second form of these decompositions, the chemical 
affinity of the acting body causes the component parts of the 
decomposing body to combine, so as to form new compounds, of 
which either both, or only one, combine with the acting body. 
Let us take dry wood, for example, and moisten it with sulphuric 
acid ; after a short time the wood is carbonized, while the sul- 
phuric acid remains unchanged, with the exception of its being 
united with more water than it possessed before. Now, this 
water did not exist as such in the wood, although its elements, 
oxygen and hydrogen, were present ; but by the chemical attrac- 
tion of sulphuric acid for water, they were in a certain measure 
compelled to unite in this form; and, in consequence of this, the 
carbon of the wood was separated as charcoal. 

Hydrocyanic acid and water, in contact with hydrochloric 
acid, are mutually decomposed. The nitrogen of the hydrocy- 
anic acid, and the hydrogen of a certain quantity of the water, 
unite together and form ammonia ; whilst the carbon and hydro- 
gen of the hydrocyanic acid combine with the oxygen of the 
water and produce formic acid. The ammonia combines with 
the muriatic acid. Here the contact of muriatic acid with water 
and hydrocyanic acid causes a disturbance in the attraction of 
the elements of both compounds, in consequence of which they 
arrange themselves into new combinations, one of \\liich — am- 
monia — possesses the power of uniting with the acting body. 

Inorganic chemistry can present instances analogous to this 
class of decomposition also ; but there are forms of organic che- 
mical decomposition of a very different kind, in which none of 
llie component parts of the decomposing matter enter into combi- 



EXAMPLES. 267 



nation v/ith the body which determines the decomposition. In 
cases of this kind a disturbance is produced in the mutual attrac- 
tion of the elements of a compound, and they, in consequence, 
arrange themselves into one or into several new combinations, 
which are incapable of suffering further change under the same 
conditions. 

When, by means of the chemical affinity of a second body, by 
the influence of heat, or through any other causes, the composi- 
tion of an organic compound is made to undergo such a change, 
that its elements form two or more new compounds, this manner 
of decomposition is called a chemical transformation or meta- 
morphosis. It is an essential character of chemical transforma- 
tions, that none of the elements o( the body decomposed are 
singly set at liberty. 

The changes designated by the terms ferbientation, decay, 
and putrefaction, are chemical transformations effected by an 
agency which has hitherto escaped attention, but the existence 
of which will be proved in the following pages 



268 CHEMICAL TRANSFORMATIONS. 



CHAPTER II. 

On the Causes which effect Fermentation, Decay,* and Putrefaction. 

Attention has been only recently directed to the fact, that a 
body in the act of combination or decomposition exercises an in- 
fluence upon any other body with which it may be in contact. 
Platinum, for example, does not decompose nitric acid ; it may 
be boiled with this acid without being oxidized by it, even when 
in a state of such fine division that it no longer reflects light 
(black powder of platinum). But an alloy of silver and platinum 
dissolves with great ease in nitric acid : the oxidation which the 
silver suffers, causes the platinum to undergo the same change ; 
or, in other words, the latter body, from its contact with the 
oxidizing silver, acquires the property of decomposing nitric 
acid. 

Copper does not decompose water, even when boiled in 
dilute sulphuric acid ; but an alloy of copper, zinc, and nickel, 
dissolves easily in this acid with evolution of hydrogen gas. 

Tin decomposes nitric acid with great facility, but water with 
difficulty ; and yetj when tin is dissolved in nitric acid, hydro- 
gen is evolved at the same time, from a decomposition of the 
water contained in the acid, and ammonia is formed in addition 
to oxide of tin. 

In the examples here given, the only combination or decompo- 
sition which can be explained by chemical affinity 's the last. In 
the other cases, electrical action ought to have retarded or pre- 

* An essential distinction is drawn in the following part of the work, 
between decay and putrcfactioji ( Verwesiing und Fiiulniss), and they are 
shown to depend on different causes ; but as the word decay is not gene- 
rally applied to a distinct species of decomposition, and does not indicate 
its true nature, I shall in future, at the suggestion of the author, employ 
the term eremacausis (from rtpina by degrees, and (taCctj burring). — Ed. 



THEIR CAUSE. 269 



vented the oxidation of the platinum or copper while they were 
in contact with silver or zinc, but, as experience shows, the in- 
fluence of the opposite electrical conditions is more than counter 
balanced by chemical action. 

The same phenomena are seen in a less dubious form ii. com- 
pounds, the elements of which are held together by a feeble 
affinity. It is well known that thei'e are chemical compounds, 
of so unstable a nature, that changes in temperature and elec- 
trical condition, or even simple mechanical friction, or contact 
with bodies apparently totally indifferent, cause such a disturb- 
ance in the attraction of their constituents, that the latter enter 
into new forms, without any of them combining with the acting 
body. These compounds appear to stand but just within the 
limits of chemical combination, and agents exercise a powerful in- 
fluence on them, which are completely devoid of action on com- 
pounds of a stronger affinity. Thus, by a slight increase of tem- 
perature, the elements of hypochlorous acid separate from one 
another with evolution of heat and light ; chloride of nitrogen 
explodes by contact with many bodies, which combine neither 
with chlorine nor nitrogen at common temperatures ; and the 
contact of any solid substance is sufficient to cause the explosion 
of iodide of nitrogen, or of fulminating silver. 

It has never been supposed that the causes of the decomposition 
of these bodies should be ascribed to a peculiar power, different 
from that which regulates chemical affinity, — a power which 
mere contact with the down of a feather is sufficient to set in 
activity, and which, once in action, gives rise to the decom- 
position. The substances have always been viewed as chemical 
compounds of a very unstable nature, in which the component 
parts are in a state of such tension, that the least disturbance 
overcomes their chemical affinity. They exist only by the vis 
ineriicR, and any shock or movement is sufficient to destroy the 
attraction of their component parts, and consequently their ex- 
istence as definite compounds. 

Peroxide of hydrogen belongs to this class of bodies ; it is 
decomposed by all substances capable of attracting oxygen from 
it, and even by contact with many bodies, such as platinum or 
silver, which do not enter "nto combination with any of its con 



270 CHEMICAL TRANSFORMATIONS. 

stituents. In this respect, its decomposition depends evidently 
upon the same causes as those which effect that of iodide of ni- 
trogen, or of fuhninating silver. Yet it is singular that the cause 
of the sudden separation of the component parts of peroxide of 
hydrogen has been viewed as dilferent from those of common 
decomposition, and has been ascribed to a new power termed the 
CATALYTIC FORCE. Now, it has Hot becu considered, that the 
presence of the platinum and silver serves here only to accele- 
rate the decomposition ; for without the contact of these metals, 
the peroxide of hydi-ogen decomposes spontaneously, although 
very slovvly. The sudden separation of the constituents of per- 
oxide of hydrogen differs from the decomposition of gaseous 
hypochlorous acid, or solid iodide of nitrogen, only in so far as 
the decomposition takes place in a liquid. 

A remarkable action of peroxide of hydrogen has attracted 
much attention, because it differs from ordinary chemical phe- 
nomena. This is the reduction which certain oxides suffer by 
contact with this substance, on the instant at which the oxygen 
separates from the water. The oxides thus easily reduced, are 
those of which the whole, or part at least, of their oxygen is re- 
tained merely by a feeble affinity, such as the oxides of silver 
and of gold, and peroxide of lead. 

Now, other oxides very stable in composition, effect the decom- 
position of peroxide of hydrogen, without experiencing the small- 
est change ; but when oxide of silver is employed to effect the 
decomposition, all the oxygen of the silver is carried away with 
that evolved from the peroxide of hydrogen, and as a result of 
the decomposition, water and metallic silver remain. When 
peroxide of lead is used for the same purpose, half its oxygen 
escapes as a gas. Peroxide of manganese may in the same man- 
ner be reduced to the protoxide, with the liberation of oxygen, if 
there be present an acid to exercise an affinity for the protoxide 
and convert it into a soluble salt. If, for example, we add to 
peroxide of hydrogen sulphuric acid, and then peroxide of 
manganese in the state of fine powder, much more oxygen is 
evolved than the compound of oxygen and hydrogen could yield ; 
and on examining the solution, we find a salt of the protoxide of 



TK EIR CAUSE. 271 



manganese, so that half of the oxygen has been evolved from the 
peroxide of that metal. 

A similar phenomenon occurs, when carbonate of silver is 
treated with several organic acids. Pyruvic ccid, for example, 
combines readily with pure oxide of silver, and forms a salt of 
sparing solubility in water. But when this acid is brought in 
contact with carbonate of silver, the oxygen of part of the oxide 
escapes with the carbonic acid, and metallic silver remains in 
the state of a black powder. (Berzelius.) 

Now no other explanation of these phenomena can be given, 
than that a body m the act of combination or decomposition ena- 
bles another body, with which it is in contact, to enter into the 
same state. It is evident that the active state of the atoms of 
one body has an influence upon the atoms of a body in con- 
tact with it ; and if these atoms are capable of the same change 
as the former, they likewise undergo that change ; and combina- 
tions and decompositions are the consequence. But when the 
atoms of the second body are not of themselves capable of such 
an action, any further disposition to change ceases from the 
moment at which i:.e atoms of the first body assume the state of 
rest, that is, when the changes or transformations of this body are 
quite completed. 

This influence exerted by one compound upon the other, is 
exactly similar to that which a body in the act of combustion 
exercises upon a combustible body in its vicinity ,• with this dif- 
ference only, that the causes which determine the commencement 
and duration of the condition of change are different. For the 
cause^ in the case of the combustible body, is heat, which is 
generated every moment anew ; whilst in the phenomena of 
decomposition and combination, which we are considering at pre- 
sent, the cause is a body in the state of chemical action, which 
exerts the decomposing influence only so long as this action 
continues. 

Numerous facts show that motion alone exercises a consi- 
derable influence on chemical forces. Thus, the power of 
cohesion does not act in many saline solutions, even when 
they are fully saturated with salts, if they are permitted to 
cool whilst at rest. In such a case, the salt dissolved in a liquid 



372 CHEMICAL TRANSFORMATIONS. 

does not crystallize ; but when a grain of sand is thrown into 
the solution, or when it receives the slightest movemei t, the whole 
liquid becomes suddenly solid with the evolution of heat. The 
same phenomenon happens with water, for this liquid may be 
cooled much under 32° F. (0° C), if kept completely undisturbed, 
but solidifies in a moment when put in motion. 

The atoms of a body must in fact be set in motion before they 
can overcome the vis inerim so as to arrange themselves into cer- 
tain forms. A dilute solution of a salt of potash, mixed with tar- 
taric acid, yields no precipitate whilst at rest ; but if the motion 
is communicated to the solution by agitating it briskly, crystals 
of cream of tartar are instantly deposited. A solution of a salt 
of magnesia also, though not rendered turbid by the addition of 
phosphate of ammonia, deposits the phosphate of magnesia and 
ammonia on those parts of the vessel touched with the rod em- 
ployed in stirring. 

In the processes of combination and decomposition under 
consideration, motion, by overcoming the vis ineriice, gives rise 
immediately to another arrangement of the atoms of a body, that 
is, to the production of a. compound which did not before exist in 
it. Of course these atoms must previously possess the power of 
arranging themselves in a certain order, otherwise both friction 
and motion would be without the smallest influence. 

The simple permanence in position of the atoms of a body, 
is the reason that so many compounds appear to present themselves, 
in conditions, and with properties, different from those which 
they possess when they obey the natural attractions of their atoms. 
Thus sugar and glass, when melted and cooled rapidly, are 
transparent, of a conchoidal fracture, and elastic and flexible to 
a certain degree. Fut the ormer becomes dull and opaque on 
keeping, and exhibits, by cleavage, crystalline faces which belong 
to crystallized sugar. Glass assumes also the same condition, 
when kept soft by heat for a long period ; it becomes 'white, 
opaque, and so hard as to strike fire with steel. Now, in both 
these bodies, the atoms evidently have different positions in the 
two forms. In the first form their attraction did not act in the di- 
rection in which their power of cohesion was strongest. It is 
known also, that when sulphur is melted and cooled rapidly bv 



THEIR CAUSE. 273 



throwing it into cold water, it remains transparent, elastic, and so 
soft that it may be drawn out into long threads; but that, after a 
few hours or days, it becomes again hard and crystalline. 

The remarkable fact here is, that the amorphous sugar or sul- 
phur returns again into the crystalline condition, without any 
assistance from an exterior cause; a fact which shows that their 
molecules have assumed another position, and thai they possess, 
thei'efore, a certain degree of mobility, even in the condition of 
a solid. A very rapid transposition or transformation of this kind 
is seen in arragonite, a mineral which possesses exactly the same 
composition as calcareous spar, but of which the hardness and 
crystalline form prove that its molecules are arranged in a dif- 
ferent manner. When a crystal of arragonite is heated, an inte- 
rior motion of its molecules is caused by the expansion ; the 
permanence of their arrangement is destroyed ; and the crystal 
splinters with much violence, and falls into a heap of small 
crystals of calcareous spar. 

It is impossible for us to be deceived regarding the causes of 
these changes. They are owing to a disturbance of the state of 
the equilibrium, in consequence of which the particles of the 
body put in motion obey either other affinities, or their own 
natural attractions. 

But if it be true, as we have just shown it to be, that mecha- 
nical motion is sufficient to cause a change of condition in many 
bodies, it cannot be doubted that a body in the act of composition 
or decomposition is capable of imparting the same condition of 
motion or activity, in which its atoms are, to those of cei'tain 
other bodies: or, in other words, of enabling other bodies with 
which it is in contact to enter into combinations, or suffer de- 
compositions. 

The reality of this influence has been already sufficiently 
proved by the facts derived from inorganic chemistry ; but it is 
of much more frequent occurrence in the relations of organic 
matter, and causes very striking and wonderful phenomena. 

By the terms fermentation, putrefaction, and eremacausis, 

are meant those changes in form and properties which compound 

organic substances undergo when separated from the organism 

and exposed to the influence of water and a certain temperature, 

13* 



274 CHEMICAL TRANSFORMATIONS. 

Fermentation and putrefaction are examples of the kind of de- 
composition wliich we have named transformations ; the elements 
of the bodies capable of undergoing these changes arrange them- 
selves into new combinations, in which the constituents of water 
generally take a part. 

Eremacausis (or decay) differs from fermentation and putre- 
faction, inasmuch as it cannot take place without the access of 
air, the oxygen of which is absorbed by the decaying bodies. 
Hence it is a process of slow combustion, in which heat is uni- 
formly evolved, and occasionally even light. In the processes 
of decomposition termed fermentation and putrefaction, gaseous 
products are very frequently formed, which are either inodorous, 
or possess a very offensive smell. 

The transformation of those matters which evolve gaseous 
products without odor, are now, by pretty general consent, desig- 
nated by the term fermentation ; whilst to spontaneous decom- 
position of bodies which emit gases of a disagreeable smell, the 
term putrefaction is applied. But the smell is, of course, no 
distinctive character of the nature of the decomposition, for both 
fermentation and putrefaction are processes of decomposition of 
a similar kind, the one of substances destitute of nitrogen, the 
other of substances containing that element. 

It has also been customary to distinguish from fermentation 
and putrefaction a particular class of transformations, viz. those 
whose conversions and transpositions are effected without the 
evolution of gaseous products. But the conditions under which 
the products of the decomposition present themselves are purely 
accidental; there is therefore no leason for the distinction just 
mentioned. 



FERMENTATION AND PUTREFACTION. 875 



CHAPTER III. 

Fermentation and Putrefaction 

Sevehal bodies appear to enter spontaneously into the states 
of fermentation and putrefaction, particularly such as contain 
nitrogen. Now it is very remarkable that very small quantities 
of these substances, in a state of fermentation or putrefaction, 
possess the power of causing unlimited quantities of similar mat- 
ters to pass into the same state. Thus, a small quantity of the 
juice of grapes in the act of fermentation, added to a large 
quantity of the same fluid, which is not fermenting, induces the 
state of fermentation in the whole mass. So likewise the most 
minute portion of milk, paste, juice of the beet-root, flesh, or 
blood, in the state of putrefaction, causes fresh milk, paste, juice 
of the beet-root, flesh, or blood, to pass into the same condition 
when in contact with them. 

These changes evidently differ from the class of common de- 
compositions effected by chemical affinity ; they are chemical 
actions, conversions, or decompositions, excited by contact with 
bodies already in the same condition, in which the elements, in 
consequence of the disturbance, arrange themselves anew, ac- 
cording to their affinities. In order to form a clear idea of these 
processes, analogous but less complicated phenomena must pre- 
viously be studied. 

The compound nature of the molecules of an organic body, 
and the phenomena presented by them when in relation with other 
matters, point out the true cause of these transformations. Evi- 
dence is afforded even by simple bodies, that in the formation of 
combinations, the force with which the combining elements ad- 
here to one another is inversely propoi'tional to the number of 
simple atoms in the compound molecule. Thus, protoxide of 



27C CHEMICAL TRANSFORMATIONS. 

manganese by absorption of oxygen is converted into the sesqui 
oxide, the peroxide, manganic and hypermanganic acids, the 
number of atoms of oxygen being augmented by ^, by 2, by 3, 
and by 3-2-. But all the oxygen contained in these compounds, 
beyond that which belongs to the protoxide, is bound to the man- 
ganese by a much more feeble affinity ; a red heat causes an 
evolution of oxygen from the peroxide, and the manganic and 
hypermanganic acids cannot be separated from their bases with- 
out undergoing imme-diate decomposition. 

There are many facts which prove, that the most simple inor- 
ganic compounds are also the most stable, and undergo decom- 
position with the greatest difficulty, whilst those of a complex 
composition yield easily to changes and decompositions. The 
cause of this evidently is, that in propoi'tion to the number of 
atoms which enter into a compound, the directions in which their 
attractions act will be more numerous. 

Whatever ideas we may entertain regarding the infinite divisi- 
bility of matter in general, the existence of chemical proportions 
removes every doubt respecting the presence of certain limited 
groups or masses of matter which we have not the power of divid- 
ing. The particles of matter called equivalents in chemistry 
are not infinitely small, for they possess a weight, and are capa- 
ble of arranging themselves in the most various ways, and of thus 
forming innumerable compound atoms. The properties of these, 
compound atoms differ in organic nature, not only according to 
the form, but also in many instances according to the direction 
and place, which the simple atoms take in the compound mole- 
cules. 

When we compare the composition of organic compounds with 
inorganic, we are quite amazed at the existence of combinations, 
in one single molecule of which, ninety or several hundred atoms 
or equivalents are united. Thus, the compound atom of an or- 
ganic acid of very simple composition, acetic acid for example, 
contains twelve equivalents of simple elements ; one atom of kinic 
acid contains thirty-three ; one of sugar thirty-six ; one of amyg- \ 
dalin ninety ; and one of stearic acid 138 equivalents. The 
component parts of animal boaies are infinitely more complex 
even than these. 



OF ORGANIC COMPOUNDS. 277 

Inorganic compounds differ from organic in as great a degree 
in their other characters as in their simplicity of constitution. 
Thus, the decomposition of a compound atom, as of sulphate of 
potash, is aided b}^ numerous causes, such as the power of cohe- 
sion, or the capability of its constituents to form solid, insoluble, 
or at certain temperatures volatile compounds with the body 
brought into contact with it, and nevertheless a vast number of 
other substances produce in it not the slightest change. Now, in 
the decomposition of a complex organic atom, there is nothing 
similar to this. 

The empirical formula of sulphate of potash is SKO4. It con- 
tains only 1 eq. of sulphur, and 1 eq. of potassium. We may 
suppose the oxygen to be differently distributed in the compound, 
and by a decomposition we may remove a part or all of it, or re- 
place one of the constituents of the compound by another sub- 
stance. But we cannot produce a different arrangement of the 
atoms, because they are already disposed in the simplest form in 
which it is possible for them to combine. Now, let us compare 
the composition of sugar of grapes with the above : here 12 eq. 
of carbon, 12 eq. of hydrogen, and 12 eq. of oxygen, are united 
together, and we know that they are capable of combining with 
each other in the most various ways. From the formula of sugar, 
we might consider it either as a hydrate of carbon, wood, starch, 
or sugar of milk, or further, as a compound of ether with alcohol, j 
or of formic acid with sachulmin.* Indeed we may calculate ' 
almost all the known organic cpmpouiids destitute of nitrogen 
from sugar, by simply adding the elements of water, or by re- 
placing any one of its elementary constituents by a different sub- 
stance. The elements necessary to form these compounds are 
therefore contained in the sugar, and they must also possess the 
power of forming numerous combinations amongst themselves by 
their mutual attractions. 

Now, when we examine what changes sugar undergoes when 
brought into contact with other bodies which exercise a marked 
influence upon it, we find that these changes are not confined to 

• The black precipitate obtained by the action of hydrochloric acid on 
sugar 



278 CHEMICAL TRANSFORMATIONS. 

any narrow limits, like those of inorganic bodies, but are in fact 
unlimited. 

The elements of sugar yield to every attraction, and to each 
in a peculiar manner. In inorganic compounds, an acid acta 
upon a particular constituent of the body which it decomposes, 
by virtue of its affinity for that constituent, and never resigns its 
proper chemical character, in whatever form it may be applied. 
But when it acts upon sugar, and induces great changes in thai 
compound, it does this not by any superior affinity for a base ex- 
isting in the sugar, but by disturbing the equilibrium in the mu- 
tual attraction of the elements of the sugar amongst themselves. 
Muriatic and sulphuric acids, which differ so much from one 
another, both in characters and composition, act in the same 
manner upon sugar. But the action of both vai'ies according to 
the state in which they are ; thus, they act in one way when di- 
lute, in another when concentrated, and even differences in their 
temperature cause a change in their action. Thus, sulphuric 
acid of a moderate degree of concentration converts sugar into a 
black carbonaceous matter, forming at the same time acetic and 
formic acid. But when the acid is more diluted, the sugar is 
converted into two brown substances, both of them containing 
carbon and the elements of water. Again, when sugar is sub- 
jected to the action of alkalies, a whole series of different new 
products are obtained ; while oxidizing agents, such as nitric acid, 
produce from it carbonic acid, acetic acid, formic acid, sac- 
charic acid, and many other products which have not yet been 
examined. 

If, from the facts here stated, we estimate the power with which 
the elements of sugar are united together, and judge of the force 
of their attraction by the resistance which they offer to the action 
of bodies brought into contact with them, we must regard the atom 
of sugar as belonging to that class of compound atoms, which exist 
only by the vis inertice, of their elements. Its elements seem 
merely to retain passively the position and condition in which they 
had been placed, for we do not observe that they resist a change 
of this condition by their own mutual attraction, as is the cast- 
with sulphate of potash. 

Now it is only such compounds as sugar, compounds there 



OF ORGANIC COMPOUNDS. 273 

fore possessing a very complex molecule, which are capable 
of undergoing the decompositions named fermentation and putre- 
faction. 

We have seen that certain metals acquire a power which they 
do not of themselves possess, namely, that of decomposing watei 
and nitric acid, by simple contact with other metals in the act of 
chemical combination. We have also seen, that peroxide of 
hydrogen and the persulphuret of the same element, in the act of 
decomposition, cause other compounds of a similar kind, but of 
which the elements are much more strongly combined, to undergo 
the same decomposition, although they exert no chemical affinity 
or attraction for them or their constituents. The cause pro- 
ducing these phenomena will be also recognised, by attentive ob- 
servation, in those matters which excite fermentation or putrefac- 
tion. All bodies in the act of combination or of decomposition 
have the property of inducing those processes ; or, in other words, 
of causing a disturbance of the statical equilibrium in the attrac- 
tions of the elements of complex organic molecules, in consequence 
of which those elements group themselves anew, according to 
their special afRnities. 

The proofs of the existence of this cause of action can be easily 
produced ; they are found in the characters of the bodies which 
effect fermentation and putrefaction, and in the regularity with 
which the distribution of the elements takes place in the subse- 
quent transformations. This regularity depends exclusively on 
the unequal affinity which they possess for each other in an 
isolated condition. The action of water on wood, charcoal, and 
cyanogen, the simplest of the compounds of nitrogen, suffices to 
illustrate the whole of the transformations of organic bodies ; of 
those in which nitrogen is a constituent, and of those in which it 
is absent. 



^SO CHEMICAL TRANSF'ORMATIONS. 



CHAPTER IV. 

On the Transformation of bodies which do not contain Nitrogen as j 
constituent ; and of those in which it is present. 

When oxygen and hydrogen, combined in equal equivalents, as 
in steam, are conducted over charcoal, heated to the temperature 
at which it possesses the power to enter into combination with one 
of these elements, a decomposition of the steam ensues. An 
oxide of carbon (either carbonic oxide or carbonic acid) is under 
all circumstances formed, while the hydrogen of the water is 
liberated. This proves that the attraction between carbon and 
oxygen is more powerful, at a high temperature, than that be- 
tween oxygen and hydrogen. The carbon here is not shared 
between the elements of the water • for no carburetted hydrogen 
is formed. 

Acetic and meconic* acids suffer a true transformation under 
the influence of heat, that is, their component elements are dis- 
united, and form new compounds without any of them being 
singly disengaged. Acetic acid is converted into acetone and 
carbonic acid C4 H3 03=03 H3 O + COg), and meconic acid 
into carbonic acid and komenic acid ; whilst, by the influence 
of a higher temperature, the latter is further decomposed into 
pyro-meconic acid and carbonic acid. 

Now, in these cases, the carbon of the bodies decomposed is 
shared between the oxygen and hydrogen ; part of it unites wuh 
the oxygen and forms carbonic acid, whilst the other portion en- 
ters into combination with the hydrogen, and an oxide of a hydro- 
carbon is formed, in which all the hydrogen is contained. 

In a similar manner, when alcohol is exposed to a gentle red 
heat, its carbon is shared between the elements of the water ; 

* An acid existing in opium, and named from the Greek for poppy. 



OF BODIES NOT CONTAINING NITROGEN. 2S1 

an oxide of a hydro-carbon which contains all the oxygen 
(aldehyde), and some gaseous compounds of carbon and hydro- 
gen, being produced. 

It is evident that during the transformation caused by heat, no 
foreign affinities can be in play, so that the new compounds must 
result merely from the elements arranging themselves, accord- 
ing to the degree of their mutual affinities, into new combina- 
tions, which are constant and unchangeable in the conditions 
under which they were originally formed, but undergo changes 
when these conditions become different. If we compare the pro- 
ducts of two bodies, similar in composition but different in pro- 
perties, subjected to transformations under the influence of two 
different causes, we find that the manner in which the atoms are 
transposed is absolutely the same in both. 

In the transformation of wood in marshy soils, by what 
we call putrefaction, its carbon is shared between the oxygen 
and hydrogen of its own substance, and of the water : car- 
burctted hydrogen is consequently evolved, as well as carbonic 
acid, both of which compounds have an analogous composition 
(CH„ CO,). 

Thus also, in the transformation of sugar called fermentation, 
its elements are divided into two portions ; the one, carbonic acid, 
contains f of the oxygen of sugar ; and the other, alcohol, con- 
tains all its hydrogen. 

In the transformation of acetic acid, produced by a red heat, 
carbonic acid, containing f of the oxygen of the acetic acid, is 
formed, and acetone, containing all its hydrogen. 

It is evident, from these facts, that the elements of a complex 
compound are left to their special attractions whenever their 
equilibrium is disturbed, from whatever cause this disturbance 
may proceed. It appears also, that the subsequent distribution 
of the elements, so as to form new combinations, always takes 
place in the same way, with this difference only, that the nature 
of the products formed is dependent upon the number of a1oms 
of the elements entering into action ; or, in other words, thai 
the products differ ad injinitum, according to the composition of 
•he oriornial substance. 



282 CHEMICAL TRANSFORMATIONS. 



ON THE TRANSFORMATION OF BODIES CONTAINING 
NITROGEN. 

By the examination of the substances most prone to fermenta- 
tion and putrefaction, it is found that they are all, without excep- 
tion, bodies containing nitrogen. In many of these compounds, 
a transposition of their elements occurs spontaneously as soon as 
they cease to form part of a living organism ; that is, when they 
are drawn out of the sphere of attraction in which alone they are 
able to exist. 

There are, indeed, bodies destitute of nitrogen which possess 
a certain degree of stability only when in combination, but which 
are unknown in an isolated condition, because their elements, 
freed from the power by which they were held together, arrange 
themselves according to their own natural attractions. Hyper- 
manganic, manganic, and hyposulphurous acids, belong to this 
class of substances, which however are rare. 

The case is very different with azotized bodies. It would 
appear that there is, in the nature of nitrogen, some peculiarity 
which gives its compounds the power to decompose spontaneously 
with so much facility. Now, nitrogen is known to be the most 
indifferent of all the elements : it evinces no particular attraction 
^, to any one of the simple bodies : and this character it preserves 
'I in all its compounds, a character which explains the cause of its 
easy separation from the matters with which it is united. 

It is only when the quantity of nitrogen exceeds a certain 
limit, that azotized compounds have some degree of permanence, 
as is the case with melamin, ammelin, &;c. Their liability to 
change is also diminished, when the quantity of nitrogen is very 
small in proportion to that of the other elements with which it is 
united, so that their mutual attractions preponderate. 

This easy transposition of atoms is best seen in the fulminating 
silvers, in fulminating mercury, in the iodide or chloride of nitro- 
gen, and in all fulminating compounds. 

All other azotized substances acquire the same power of de- 
composition, when the elements of water are brought into play ; 
and indeed the greater part of tliem are not capable of trans. 



OF BODIES CONTAINING NITROGEN. 283 

formation, while this necessary condition to the transposition of 
their atoms is absent. Even the compounds of nitrogen most 
liable to change, such as those found in animal bodies, do not 
enter into a state of putrefaction when dry. 

The result of the known transformations of azotized substances 
proves, that water does not merely act as a medium in which 
motion is permitted to the elements in the act of transposition, (i 
but that its influence depends on chemical affinity. When the 
decomposition of such substances is effected with the assistance 
of water, their nitrogen is invariably liberated in the form of 
ammonia. This is a fixed rule, without any exceptions, what- 
ever may be the cause which produces the decompositions. All , , 
organic compounds containing nitrogen evolve the whole of that ] 
element in the form of ammonia, when acted on by alkalies. ^ 
Acids and increase of temperature produce the same effect. It 
is only when there is a deficiency of water, or of its elements, 
that cyanogen or other azotized compounds are produced. 

From these facts it may be concluded, that ammonia is the 
most stable compound of nitrogen ; and that hydrogen and nitro- 
gen possess a degree of affinity for each other surpassing the 
attraction of the latter body for any other element. 

Already in considering the transformations of substances des- 
titute of nitrogen, we have recognised the great affinity of carbon 
for oxygen as a powerful cause for effecting the disunion of the 
elements of a complex organic atom in a definite manner. But 
carbon is also invariably contained in azotized organic com- i; 
pounds, while the great affinity of nitrogen for hydrogen fur- |' 
nishes a new and powerful cause of change, and thus facilitates 
the transposition of their component parts. Thus, in the bodies 
destitute of nitrogen we have one element, and in those contain- 
ing that substance, two elements which mutually share the ele- 
ments of water. Hence there are two opposite affinities at play, 
which mutually strengthen each other's action. 

Now we know, that the most powerful attractions may be over- 
come by the influence of two affinities. Thus, a decomposition 
of alumina may be effected with the greatest facility, when the 
affinity of charcoal for oxygen, and of chlorine for aluminium, 
are both put in action, although neither of these alone has anv 



284 CHEMICAL TRAISiSFORMATIONS. 

influence upon it. There is in the nature and constitution of the 
compounds of nitrogen a kind oi tension of their component 
parts, and a strong disposition to yield to transformations, which 
effect spontaneously the transposition of their atoms from the 
instant that water or its elements are brought in contact with 
them. 

The characters of the hydrated cyanic acid, one of the sim- 
plest of all the compounds of nitrogen, are perhaps the best 
adapted to convey a distinct idea of the manner in which the 
atoms are disposed of in transformations. This acid contains 
carbon, nitrogen, hydrogen, and oxygen, in such proportions, that 
the addition of a certain quantity of the elements of water is ex- 
actly sufficient to cause the oxygen contained in the water and 
acid to unite with the carbon and form carbonic acid, and the 
hydrogen of the water and acid to combine with the nitrogen and 
l[ form ammonia. The most favorable conditions for a complete 
'* transformation are, therefore, associated in these bodies, and it is 
well known that the disunion takes place on the instant in which 
the cyanic acid and water are brought into contact, the mixture 
being converted into carbonic acid and ammonia, with brisk effer- 
vescence. 

This decomposition may be considered as the type of the trans- 
formations of all azotized compounds ; it is putrefaction in its 
simplest and most perfect form, because the new products, the 
carbonic acid and ammonia, are incapable of further transforma- 
tions. 

Putrefaction assumes a totally different and much more con.- 
plicated form, when the products at first formed undergo a further 
change. In these cases the process consists of several stages, of 
which it is impossible to determine when one ceases and the other 
begins. 

The transformations of cyanogen, a body composed of carbon 
s and nitrogen, and the simplest of all the compounds of nitrogen, 
' ' will convey a clear idea of the great variety of products which 
are produced in such a case : it is the only example of the pu- 
trefaction of an azotized body which has been at all accurately 
studied. 

A solution of cyanogen in water becomes turbid after a short 



OF BODIES CONTAINING NITROGEN. 285 

time, and deposits a black, or brownish black matter, which is a 
combination of ammonia with another body, produced by the 
simple union of cyanogen with water. This substance is inso- 
luble in water, and is thus enabled to resist further change. 

A second transformation is effected by the cyanogen being 
shared between the elements of the water, in consequence of 
which CYANIC ACID is formed by a certain quantity of the cyano- 
gen combining with the oxygen of the water ; while hydrocya- 
nic ACID is also formed, by another portion of the cyanogen unit- 
ing with the hydrogen thus liberated. 

Cyanogen experiences a third transformation, by which a com- 
plete disunion of its elements takes place, these being divided 
between the constituents of the water. Oxalic acid is the one 
product of this disunion, and ammonia the other. 

Cyanic acid, the formation of which has been mentioned above, 
cannot exist in contact with water, being decomposed immedi- 
ately into carbonic acid and ammonia. The cyanic acid, how- 
ever, newly formed in the decomposition of cyanogen, escapes 
this decomposition by entering into combination with the free am- 
monia, by which means ttrea is produced. 

The hydrocyanic acid is also decomposed into a brown matter 
containing hydrogen and cyanogen, the latter in greater propor- 
tion than in the gaseous hydrocyanic acid. Oxalic acid, urea, 
and carbonic acid, are also formed by its decomposition, and 
FORMIC ACID and AMMONIA are produced by the decomposition of 
its radical. 

Thus, a substance consisting of only two elements (carbon and 
nitrogen) yields, in contact with water, eight totally different pro- 
ducts. Several of these products are formed by the transforma- 
tion of the original body, its elements being shared between the 
constituents of water ; others are produced in consequence of a 
further change in those first formed. The urea and carbonate 
of ammonia are generated by the combination of two of the 
products, and in their formation the whole elements have as- 
sisted. 

These examples show that the results of decomposition by fer- 
mentation and putrefaction comprehend very different pheno- 
mena. The first kind of transformation is the transposition of 



886 CHEMICAL TRANSFORMATIONS. 

tlie elements of one complex compound, by which new com- 
pounds are produced with or without the assistance of the ele- 
ments of water. In the products newly formed in this manner, 
either the same proportions of those component parts which 
were contained in the matter before transformation are found, 
or with them an excess, consisting of the constituents of water 
which had assisted in promoting the disunion of the elements. 

The second kind of transformations consists of the transposi- 
tions of the atoms of two or more complex compounds, by which 
the elements of both arrange themselves mutually into new pro- 
ducts, with or without the co-operation of the elements of water. 
In this kind of transformations, the new products contain the sum 
of the constituents of all the compounds which had taken a part 
in the decomposition. 

The first kind of decomposition characterizes the proper fer- 
mentation ; the other, that which is called putrefaction. We shall, 
in the following pages, use these terms invariably for these two 
kinds of metamorphosis, which are essentially diffeient in their 
results. 



FERMENTATION OF SUGAR. 3S7 



CHAPTER V. 

Fermentation of Sugar. 

The peculiar decomposition of sugar may be viewed as a type 
of all the transformations designated fermentation.* 

The analysis of sugar from the cane, proves that it contains 
the elements of carbonic acid and alcohol, minus 1 atom of water. 
The alcohol and carbonic acid produced by the fermentation of 
a certain quantity of sugar, contain together one equivalent of 
oxygen and one equivalent of hydrogen ; the elements, therefore, 
of one equivalent of water more than the sugar contained. The 
excess of weight in the products is thus explained mxost satisfac- 
torily ; it is owing, namely, to the elements of water having taken 
part in the metamorphosis of the sugar. 

It is known that 1 atom of sugar contains 12 equivalents of 
carbon, both from the proportions in which it unites with bases, 
and from the composition of saccharic acid, the product of its 
oxidation. Now none of these atoms of carbon are contained in 

* When yeast is made into a thin paste with water, and 1 cubic centi- 
metre of this mixture introduced into a graduated glass receiver filled with 
mercury, in which are already 10 grammes of a solution of cane-sugar, 
containing 1 gramme of pure solid sugar ; it is found, after the mixture 
has been exposed for 24 hours to a temperature of from 20 to 25 C. (6S — 
77 F.), that a volume of carbonic acid has been formed, which, at O'^ C. 
(32° F.), and an atmospheric pressure indicated by 0"7G metre Bar : would 
be from 245 to 250 cubic centimetres. But to this quantity we must add 
11 cubic centimetres of carbonic acid, with which the 11 grammes of liquid 
would be saturated ; so that in all, 256 — 261 cubic centimetres of carbonic 
acid are obtained. This volume of carbonic acid corresponds to from 
0"503 to 0"5127 grammes by weight. Thenard also obtained from 1 gramme 
of sugar 0'5262 grammes of absolute alcohol. 100 parts of cane-sugar 
yield, therefore, of alcohol and carbonic acid together 103'S9 parts. Now 
in these two products are contained 42 parts of carbon, or exactly tha 
quantity originally present in the sugar. 



888 FERMENTATION OF SUGAR. 

the sugar as carbonic acid, because the whole quantity is obtainea 
as oxalic acid, when sugar is treated with hypermanganate of pot- 
ash (Gregory) ; and as oxalic acid is a lower degree of the oxi- 
dation of carbon than carbonic acid, it is impossible to conceive 
that the lower degree should be produced from the higher, by 
means of one of the most powerful agents of oxidation which we 
possess. 

It can be also proved, that the hydrogen of the sugar does not 
exist in it in the form of alcohol, for it is convei'ted into water 
and a kind of carbonaceous matter, when treated with acids, 
particularly with such as contain no oxygen ; and this manner 
of decomposition is never suffered by a compound of alcohol. 

Sugar contains, therefore, neither alcohol nor carbonic acid, so 
that these bodies must be produced by a different arrange- 
ment of its atoms, and by their union with the elements of 
water. 

In this metamorphosis of sugar, the elements of the yeast, by 
contact with which its fermentation was effected, take no ap- 
preciable part in the transposition of the elements of the sugar ; 
for in the products resulting from the action, we find no compo- 
nent part of this substance. The same sugar which in contact 
with yeast yields alcohol and cai'bonic acid gives rise, when in 
contact with putrefying white cheese, to butyric acid, hydrogen 
being at the same time liberated. (Pelouse and Gelis.) 

We may now study the fermentation of a vegetable juice, con- 
taining not only saccharine matter, but also such substances as 
albumen and gluten. The juices of parsneps, beet-roots, and 
onions, are well adapted for this purpose. When such a juice is 
mixed with yeast at common temperature, it ferments like a solu- 
tion. Carbonic acid gas escapes from it with effervescence, and 
in the liquid, alcohol is found in quantity exactly corresponding 
to that of the sugar originally contained in the juice. But such 
a juice undergoes spontaneous decomposition at a temperature of 
from 95° to 104° (35° — 40° C). Gases possessing an offensive 
smell are evolved in considerable quantity, and when the liquor 
is examined after the decomposition is completed, no alcohol can 
be detected. The sugar has also disappeared, and with it all the 
azotized compounds which existed in the juice previously to its 



YEAST OR FERMENT. 2S9 

fermentation. Both were decomposed at the same time ; the 
nitrogen of the azotized compounds remains in the liquid as am- 
monia, and, in addition to it, there are three new products, formed 
from the component parts of the juice. One of these is lactic 
acid, the slightly volatile compound found in putrid animal mix- 
tures ; the other is the crystalline body which forms the principal 
constituent of manna ; and the third is a mass resembling gum- 
arabic, which forms a thick viscous solution with water. These 
three products weigh more than the sugar contained in the juice, 
even without calculating the weight of the gaseous products. 
Hence they are not produced from the elements of the sugar 
alone. None of these three substances could be detected in the 
juice before fermentation. They must, therefore, have been 
formed by the interchange of the elements of the sugar with 
those of the foreign substances also present. It is this mixed 
transformation of two or more compounds which receives the 
special name of putrefaction. 



YEAST OR FERMENT. 



When attention is directed to the condition of those substances 
which possess the power of inducing fermentation and putre- 
faction in other bodies, evidence is found in their general 
characters, and in the manner in which they combine, that 
they all are bodies, the atoms of which are in the act of trans- 
position. 

The characters of the remarkable matter deposited in an inso 
luble state during the fermentation of beer, wine, and vegetable 
juices, may first be studied. 

This substance, called yeast or ferment, from the power 
which it possesses of causing fermentation in sugar, or saccha- 
rine vegetable juices, possesses all the characters of a com- 
pound OF NITROGEN IN THE STATE OF PUTREFACTION AND KREMA- 
CACSIS. 

14 



490 YEAST OR FERMENT. 

Like wood in the state of eremacausis, yeast converts the 
oxygen of the surrounding air into carbonic acid, but it also 
evolves this gas from its own mass, like bodies in the state of 
putrefaction. (Colin.) When kept under water, it emits car- 
bonic acid, accompanied by gases of an offensive smell (Thenard), 
and is at last converted into a substance resembling old cheese 
(Proust). But when its own putrefaction is completed, it has no 
longer the power of inducing fermentation in other bodies. The 
presence of water is quite necessary for sustaining the proper- 
ties of ferment, for by simple pressure its power to excite fer- 
mentation is much diminished, and is completely destroyed by 
A drying. Its action is arrested also by the temperature of boiling 
water, by alcohol, common salt, an excess of sugar, oxide of 
mercury, corrosive sublimate, pyroligneous acid, sulphurous 
acid, nitrate of silver, volatile oils, and in short, substances, all 
of which possess antiseptic properties. 

The insoluble part of the substance called ferment does 

NOT cause fermentation. For when the yeast from wine or 

beer is carefully washed with water, care being taken that it is 

/ is always covered with this fluid, the residue does not produce fer- 

mentation. 

The soluble part of ferment likewise does not excite 
fermentation. An aqueous infusion of yeast may be mixed 
with a solution of sugar, and preserved in vessels from which the 
air is excluded, without either experiencing the slightest change. 
What then, we may ask, is the matter in ferment which excites 
fermentation, if neither the soluble nor insoluble parts possess the 
power ? This question has been answered by Colin in the most 
satisfactory manner. He has shown that in reality it is the 
SOLUBLE PART. But before it obtains this power, the decanted 
infusion must be allowed to cool in contact with the air, and to 
fl\ remain some time exposed to its action. When introduced into 
a solution of sugar in this state, it produces a brisk fermentation ; 
but without previous exposure to the air, it manifests no such 
property. 

The infusion absorbs oxygen during its exposure to the air, 
and cnrbonic acid may be found in it after a short time. 

Yeast produces fermentation in consequence of the pio- 



ITS PROPERTIES. 291 



gressive decomposition which it suffers from the action of ail , 
and water. 

Now when yeast is made to act on sugar, it is found that 
after the completion of the transformation of the latter substance 
into carbonic acid and alcohol, part of the yeast itself has dis- 
appeared. 

From 20 parts of fresh yeast from beer, and 100 parts of 
sugar, Thenard obtained, after the fermentation was completed, 
13-7 parts of an insoluble residue, which diminished to 10 parts 
when employed in the same way, with a fresh portion of sugar. 
These ten parts were white, possessed of the properties of woody 
fibre, and had no further action on sugar. 

It is evident, therefore, that, during the fermentation of sugar 
by yeast, both of these substances suffer decomposition at the 
same time, and disappear in consequence. But if yeast be a 
body which excites fermentation by being itself in a state of 
decomposition, all other matters in the same condition should 
have a similar action upon sugar ; and this is in reality the case. 
Muscle, urine, isinglass, osmazome, albumen, cheese, gliadine, 
gluten, legumin, and blood, when in a state of putrefaction, all 
have the power of producing the putrefaction or fermentation of 
a solution of sugar. Yeast, which by continued washing has 
entirely lost the property of inducing fermentation, regains it 
when its putrefaction has recommenced, in consequence of its 
being kept in a warm situation for some time. 

Yeast and putrefying animal and vegetable matters act as 
peroxide of hydrogen does on oxide of silver, when they induce 
bodies with which they are in contact to enter into the same 
state of decomposition. The disturbance in the attraction of the 
constituents of the peroxide of hydrogen effects a disturbance 
in the attraction of the elements of the oxide of silver, the one 
being decomposed on account of the decomposition of the 
other. 

Peroxide of hydrogen is rapidly decomposed in contact with 
moist fibrin of blood, an animal substance in a continuous state 
of decomposition. The oxygen which it contained, in addition 
to that necessary to form water, escaped with violent effer. 
vescence. 



292 YEAST OR FERMENT. 

Now if we consider the process of the fermentation of pure 
sugar, in a practical point of view, we meet with two facts of 
constant occurrence. When the quantity of ferment is too 
small in proportion to that of the sugar, its putrefaction will be 
completed before the transformation of all the sugar is effected. 
Some sugar here remains undecomposed, because the cause of 
its transformation is absent, viz. contact with a body in a state 
of decomposition. 

But when the quantity of ferment predominates, a certain 
quantity of it remains after all the sugar has fermented, its 
decomposition proceeding very slowly, on account of its insolu- 
bility in water. This residue of ferment is still able to induce 
fermentation, when introduced into a fresh solution of sugar, 
and retains the same power until it has passed through all the 
stages of its own transformation. Hence a certain quantity of 
yeast is necessary in order to effect the transformation of a 
certain portion of sugar, not because it acts by its quantity in 
increasing any affinity, but because its influence depends solely 
on its presence, and its presence is necessary, until the last atom 
of sugar is decomposed. 

These facts and observations point out the existence of a new 
cause, which effects combinations and decompositions. This 
cause is the action which bodies in a state of combination or 
decomposition exercise upon substances, the component parts of 
which are united together by a feeble affinity. This action 
resembles a peculiar power, attached to a body in the state of 
combination or decomposition, but exerting its influence beyond 
the sphere of its own attractions. We are now able to account 
satisfactorily for many known phenomena. 

A large quantity of hippuric acid may be obtained from the 
fresh urine of a horse, by the addition of muriatic acid ; but 
when the urine has undergone putrefaction, no trace of it can 
bo discovered. The urine of man contains a considerable 
quantity of urea ; but when the urine putrefies, the urea entirely 
disappears. When urea is added to a solution of sugar in the 
state of fermentation, it is decomposed into carbonic acid and 
ammonia. No asparagin can be detected in a putrefied infusion 
of asparagus, licorice-root, or the root of marshmallow (AltJicea 
officinalis). 



DIFFERENCE OF FERMENTATION AND PUTREFACTION. 293 

It has also been mentioned, that the strong affinity of nitrogen 
for hydrogen, and that of carbon for oxygen, are the cause of the 
facility with which the elements of azotized compounds are dis- 
united ; those affinities aiding each other, inasmuch as by virtue 
of them different elements of the compounds strive to take 
possession of the different elements of water. Now since it is 
found that no body destitute of nitrogen possesses, when pure, 
the property of decomposing spontaneously whilst in contact 
with water, we must ascribe this property which azotized bodies 
possess in so eminent a degree, to something peculiar in the 
nature of the compounds of nitrogen, and to their constituting, in 
a certain measure, more highly organized atoms. 

Every azotized constituent of the animal or vegetable organism 
runs spontaneously into putrefaction, when exposed to moisture \ j 
and a high temperature. 

Azotized matters are, accordingly, the only causes of fermen- " . 
tation and putrefaction in vegetable substances. 

Putrefaction, on account of its defects, as a mixed transforma- 
tion of many different substances, may be classed with the most 
powerful processes of deoxidation, by which the strongest affini- 
ties are overcome. 

When a solution of gypsum in water is mixed with a decoc- 
tion of sawdust, or any other organic matter capable of putrefac- 
tion, and preserved in well-closed vessels, it is found after some 
time, that the solution no longer contains sulphuric acid, but in 
its place carbonic and free hydrosulphuric acids, between which 
the lime of the gypsum is shared. In stagnant water containing 
sulphates in solution, crystallized pyrites are observed to form on 
the decaying roots. 

Now we know that in the putrefaction of wood under water, 
when air therefore is excluded, a part of its carbon combines with 
the oxygen of the water, as well as with the oxygen which the 
wood itself contains ; whilst its hydrogen and that of the decom- 
posed water are liberated either in a pure state, or as carburetted 
hydrogen. 

It is evident, that if with the water a substance containing a 
large quantity of oxygen, such as sulphuric acid, be also present, 
the matters in the .state of putrefaction will make use of the oxy 



294 YEAST OR FERMENT. 



gen of that substance as well as that of the water, in order to form 
carbonic acid ; and the sulphur and hydrogen being set free will 
combine whilst in the nascent state, producing hydrosulphurie 
acid, which will be again decomposed if metallic oxides be 
present ; and the results of this second decomposition will be 
water and metallic sulphurets. 

The putrefied leaves of woad (Insatis tincioria), in contact with 
indigo-blue, water, and alkalies, suffer further decomposition, and 
the indigo is deoxidized and dissolved. 

The mannite formed by the putrefaction of the juice of the beet- 
root and other plants containing sugar, contains the same number 
of equivalents of carbon and hydrogen as the sugar of grapes, but 
two atoms leSs of oxygen ; and it is highly probable that it is pro- 
duced from sugar of grapes, contained in those plants, in precisely 
the same manner as indigo-blue is converted into deoxidized 
white indigo. 

During the putrefaction of gluten, carbonic acid and pure hy- 
drogen gases are evolved ; phosphate, acetate, caseate, and lactate 
of ammonia being at the same time produced in such quantity, 
that the further decomposition of the gluten ceases. But when 
the supply of water is renewed, the decomposition begins again, 
and in addition to the salts just mentioned, carbonate of ammonia 
and a white crystalline micaceous matter (caseous oxide) are 
formed, together with hydrosulphate of ammonia, and a mucila- 
ginous substance coagulable by chlorine. Lactic acid is almost 
always produced by the putrefaction of organic bodies. 

We may now compare fermentation and putrefaction with the 
decomposition which organic compounds suffer under the influence 
of a high temperature. Dry distillation would appear to be a 
process of combustion or oxidation going on in the interior of a 
substance, in which a part of the carbon unites with all or part 
of the oxygen of the compound, while other new compounds con- 
taining a large proportion of hydrogen are necessarily produced. 
Fermentation may be considered as a process of combustion or 
oxidation of a similar Icind. taking place in a liquid between the 
elements of the same matter, at very slightly elevated temperature ; 
and putrefaction as a process of oxidation, in which the oxygen 
of all the substances present comes into play. 



EREMACAUSIS, OR DECAY. 295 



CHAPTER VI. 

Eremacausis, or Decay. 

In organic nature, besides the processes of decomposition named 
fermentation and putrefaction, another and not less striking class 
of changes occurs, which bodies suffer from the influence of the 
air. This is the act of gradual combination of the combus- 
tible elements of a body with the oxygen of the air ; a slow 
combustion or oxidation, to which we shall apply the term of 
eremacausis. 

The conversion of wood into humus, the formation of acetic 
acid out of alcohol, nitrification, and numerous other processes, 
are of this nature. Vegetable juices of every kind, parts of ani- 
mal and vegetable substances, moist sawdust, blood, &c., cannot 
be exposed to the air, without suffering immediately a progressive 
change of color and properties, during which oxygen is absorbed. 
These changes do not take place when water is excluded, or when 
the substances are exposed to the temperature of 32°, and it has 
been observed that dilTerent bodies require different degrees of 
heat, in order to effect the absorption of oxygen, and, conse- 
quently, their eremacausis. The tendency to undergo this 
change is possessed in the highest degree by substances contain- 
ing nitrogen. 

When vegetable juices are evaporated by a gentle heat in the 
air, a brown or brownish-black substance is precipitated as a pro- 
duct of the action of oxygen upon them. This substance, which 
appears to possess similar properties from whatever juice it is ob- 
tained, has received the name o^ extractive matter ; it is insoluble 
or very sparingly soluble in water, but is dissolved with facility 
by alkalies. By the action of air on solid animal or vegetable 
matters, a similar pulverulent brown substance is formed, and ia 
known by the name of humus. 



296 EREMACAUSIS, OR DECAY; 

The conditions which determine the commencement of erema. 
causis are of various kinds. Many organic substances, par- 
ticularly such as are mixtures of several more simple matters 
oxidize in the air when simply moistened with water ; others not 
until they are subjected to the action of alkalies; but the greatest 
part of them undergo this state of slow combustion or oxidation, 
when brought in contact with other matters already in a state 
of decay. 

The eremacausis of an organic matter is retarded or completely 
arrested by all those substances which prevent fermentation or 
putrefaction. Mineral acids, salts of mercury, aromatic sub- 
stances, empyreumatic oils, and oil of turpentine, possess a simi- 
lar action in this respect. The latter substances have the same 
effect on decaying bodies as on phosphuretted hydrogen, the spon- 
taneous inflammability of which they destroy. 

Many bodies which do not decay when moistened with water, 
enter into eremacausis when in contact with an alkali. Gallic 
acid, hsematin, and many other compounds, may be dissolved in 
water and yet remain unaltered ; but if the smallest quantity of a 
free alkali is present, they acquire the property of attracting oxy- 
,gen, and are converted into a brown substance like humus, evol- 
J'ving very frequently at the same time carbonic acid. (Chevreul.) 

A very remarkable kind of eremacausis takes place in many 
vegetable substances, when they are exposed to the influence oi 
air, water, and ammonia. They absorb oxygen very rapidly, and 
form splendid violet or red-colored liquids, as in the case of orcin 
and erythrin. They now contain an azotized substance, not in 
the form of ammonia. 

All these facts show that the action of oxygen seldom affects 
the carbon of decaying substances, and this corresponds exactly 
to what happens in combustion at high temperatures. It is well 
known, for example, that when no more oxygen is admitted to a 
[; compound of carbon and hydrogen than is sufficient to combine 
with its hydrogen, the carbon is not burned, but is separated as 
lamp-black ; while, if the quantity of oxygen is not sufficient even 
to consume all the hydrogen, new compounds are formed, such 
•a naphthalin and similar maticrs, which contain a smaller pro- 



EXAMPLES OF. 297 



portion of hydrogen than those compounds of carbon and hydrogen 
which previously existed in the combustible substance. 

There is no example of carbon combining directly with ox3-gen 
at common temperatures, but numerous facts show that hydrogen, 
in certain states of condensation, possesses that property. Lamp- 
black which has been heated to redness may be kept in contact 
with oxygen gas, without forming carbonic acid ; but lamp-black, i 
impregnated with oils containing a large proportion of hydrogen,! 
gradually becomes warm, and inflames spontaneously. The j 
spontaneous inflammability of the charcoal used in the fabrication 
of gunpowder has been correctly ascribed to the hydrogen con- 
tained in it in considerable quantity ; for during its reduction to 
powder, no trace of carbonic acid can be detected in the air 
surrounding it ; it is not formed until the temperature of the 
mass has reached a red heat. The heat which produces the 
inflammation is therefore not caused by the oxidation of the 
carbon. 

The matters subject to eremacausis may be divided into two 
classes. The first class compi-ehends those substances which 
unite with the oxygen of the air, without evolving carbonic acid ; 
and the second, such as emit carbonic acid while they absorb 
oxygen. 

When the oil of bitter almonds is exposed to the air, it absorbs 
two equivalents of oxygen, and is converted into benzoic acid ; 
but half of the oxygen absorbed combines with the hydrogen of 
the oil, and forms water, which remains in union with the anhy- 
drous benzoic acid. 

According to the experiments of Dobereiner, 100 parts of 
pyrogallic acid absorb 38-09 parts of cxygen when in contact 
with ammonia and water ; the acid being changed in cop.sc- 
quence of this absorption into a mouldy substance, which contains 
less oxygen than the acid itself. It is evident that the substance 
formed is not a higher oxide ; and it is found, on comparing the 
quantity of the oxygen absorbed with that of the hydrogen con- 
tained in the acid, that they are exactly in the proportions for ;/ 
forming water. 

When colorless orcin is exposed together with ammonia to thft 
contact of oxygen gas, the beautiful red-colored orcein is produc- 
14* 



298 EREMACAUSIS, OR DECAY. 

ed. Now, the only changes which take place here are, that the 
absorption of oxygen by the elements of orcin and ammonia 
causes the formation of water ; 1 equivalent of orcin Cjg H, , 
O7, and 1 equivalent of ammonia NHg, absorb 5 equivalents 
of oxygen, and 5 equivalents cf water are produced, the compo- 
sition of orcein being Cu Hg O, N. (Dumas.) In this case 
it is evident, that the oxygen absorbed has united merely with 
the hydrogen. 

But, although it appears very probable that the oxygen acts 
primarily and principally upon hydrogen, the most combustible 
constituent of organic matter in the state of decay ; still it can- 
not thence be concluded that the carbon is quite devoid of the 
power to unite with oxygen, when every particle of it is surround- 
ed with hydrogen, an element with which the oxygen combines 
with greater facility. 

We know, on the contrary, that although nitrogen cannot be 
made to combine with oxygen directly, yet it is oxidized and 
forms nitric acid, when mixed with a large quantity of hydrogen, 
and burned in oxygen gas. In this case its affinity is evidently 
increased by the combustion of the hydrogen, which is in fact 
communicated to it. It is conceivable that, in a similar manner, 
the carbon may be directly oxidized in several cases, obtaining 
from its contact with hydrogen in eremacausis a property which 
it does not itself possess at common tempei'atures. But the 
formation of carbonic acid during the eremacausis of bodies con- 
taining hydrogen, must in most cases be ascribed to another cause. 
It appears to be formed in a manner similar to the formation of 
acetic acid, by the eremacausis of saliculite of potash. This salt, 
when exposed to a moist atmosphere, absorbs 3 atoms of oxygen ; 
tnelanic acid is produced, a body resembling humus, in conse- 
quence of the formation ot which, the elements of 1 atom of 
acetic acid are separated from the saliculous acid. 

An alkaline solution of hsematin being exposed to an atmo- 
sphere of oxygen, 0*2 grm. absorb 28-6 cubic centimeters of 
oxygen gas in twenty- four hours, the alkali acquiring at the same 
time 6 cubic centimeters of carbonic acid. (Chevreul.) But 
these 6 cubic centimeters of carbonic acid contain only an equal 
volume of oxygen, so that it is certain from this experiment that 



FORMATION OF CARBONIC iCID. 299 

5 of the oxygen absorbed have not united with the carbon. It is 
highly probable, that during the oxidation of the hydrogen, a 
portion of the carbon had united with the oxygen contained in the 
hsematin, and had separated from the other elements as carbonic 
acid. 

The experiments of De Saussure upon the decay of woody 
fibre show that such a separation is highly probable. Moist 
woody fibre evolved one volume of carbonic acid for every 
volume of oxygen which it absorbed. It has just been mentioned 
that carbonic acid contains its own volume of oxygen. Now, 
woody fibre contains carbon and the elements of water, so that 
the result of the action of oxygen upon it is exactly the same 
as if pure charcoal had combined directly with oxygen. But 
the characters of woody fibre show, that the elements of water 
are not contained in it in the form of water ; for, were this the 
case, starch, sugar, and gum must also be considered as hydrates 
of carbon. 

But if the hydrogen does not exist in woody fibre in the form 
of water, the direct oxidation of the carbon cannot be considered 
as at all probable, without rejecting all the facts established by 
experiment regarding the process of combustion at low tempera- 
tures. 

If we examine the action of oxygen upon a substance con- 
taining a large quantity of hydrogen, such as alcohol, we find 
most distinctly, that the direct formation of carbonic acid is the 
last stage of its oxidation, and that it is preceded by a series of 
changes, the last of which is a complete combustion of the hy- 
drogen. Aldehyde, acetic, formic, oxalic, and carbonic acids, 
form a connected chain of products arising from the oxidation of .•] 
alcohol ; and the successive changes which this fluid experi- ' 
ences from the action of oxygen may be readily traced in them. 
Aldehyde is alcohol minus hydrogen ; acetic acid is formed by 
the direct union of aldehyde with oxygen. Formic acid and 
water are formed by the union of acetic acid with oxygen. 
When all the hydrogen is removed from formic acid, oxalic acid 
Is produced ; and the latter acid is converted into carbonic acid 
by uniting with an additional portion of oxygen. All these pro- 
ducts appear to be formed simultaneously, by the action of oxid- 



300 EREMACAUSIS OR DECAY; 



izing agents on alcohcl ; but it can scarcely be doubted, that the 
formation of the last product, ,he carbonic acid, does not take 
placie until all the hydrogen has been abstracted. 

The absorption of oxygen by drying oils certainly does not 
depend upon the oxidation of their carbon ; for in raw walnut- 
oil, for example, which was not free from mucilage and other 
substances, only twenty-one volumes of carbonic acid were 
formed for every 146 volumes of oxygen gas absorbed. 

It must be remembered, that combustion or oxidation at low 
temperatures produces results quite similar to combustion at 
high temperatures with limited access of air. The most 
combustible element of a compound exposed to the action of 
oxygen, must become oxidized first, for its superior combustibility 
is caused by its being enabled to unite with oxygen at a tempera- 
ture at which the other elements cannot enter into that combina. 
tion ; this property having the same effect as a greater affinity. 

The combustibility of potassium is no measure of its affinity 
for oxygen ; we have reason to believe that the attraction of 
magnesium and aluminium for oxygen is greater than that of 
potassium for the same element ; but neither of those metals 
oxidizes either in air or water at common temperatures, whilst 
potassium decomposes water with great violence, and appropriates 
its oxygen. 

Phosphorus and hydrogen combine with oxygen at ordinary 
temperatures, the first in moist air, the second when in contact 
with finely-divided platinum ; while charcoal requires a red heat 
before it can enter into combination with oxygen. It is evident 
that phosphorus and hydrogen are more combustible than char- 
coal, that is, that their affinity for oxygen at common tempera- 
tures is greater ; and this is not the less certain, because it is 
found, that carbon in certain other conditions shows a much 
greater affinity for oxygen than either of those substances. 

In putrefaction, the conditions are evidently present, under 
which the superior affinity of carbon for oxygen comes into 
play ; neither expansion, cohesion, nor the gaseous state, opposes 
it, whilst in eremacausis all these restraints have to be over- 
come. 

The evolution of carbonic acid, during the decay or erema- 



ITS CAUSE. ??0i 



causis of animal or vegetable bodies which are rich in hydrogen, 
must accordingly be ascribed to a transposition of the elements 
or disturbance in their attractions, similar to that which gives 
rise to the formation of carbonic acid in the processes of fermen- 
tation and putrefaction. While the hydrogen of the substance 
is removed and oxidized by eremacausis, carbon and oxygen 
separate from the remaining elements in the form of carbonic 
acid. 

The eremacausis of such substances is, therefore, a decom 
position analogous to the putrefaction of azotized bodies. For in 
these there are two affinities at play ; the atfinity of nitrogen for 
hydrogen, and that of carbon for oxygen, and both facilitate the 
disunion of the elements. Now there are two affinities also in 
action in those bodies which decay with the evolution of carbonic 
acid. One of these affinities is the attraction of the oxygen of 
the air for the hydrogen of the substance, which corresponds to 
the attraction of nitrogen for the same element ; and the other is 
the affinity of the carbon of the substance for its oxygen, which 
is constant under all circumstances. 

When wood putrefies in marshes, carbon and oxygen are , 
separated from its elements in the form of carbonic acid, and i 
hydrogen in the form of carburetted hydrogen. But when wood I 
decays or putrefies in the air, its hydrogen does not combine with 
carbon, but with oxygen, for which it has a much greater affinity 
at common temperatures. 

Now it is evidently owing to the complete similarity of these 
processes, that decaying and putrefying bodies can mutually re- 
place one another in their reciprocal actions. 

All putrefying bodies pass into a state of decay when exposed 
freely to the air, and all decaying matters into that of putrefac- i-; 
tion when air is excluded. All bodies, likewise, in a state of 
decay are capable of inducing putrefaction in other bodies, iuihe 
same manner as putrefying bodies themselves do. 



.^02 EREMACAUSIS OR DECAY. 



CHAPTER VII. 

Eremacausis or decay of bodies destitute of Nitrogen : formation of 
Acetic Acid. 

All those substances which appear to possess the property of 
entering spontaneously into fermentation and putrefaction, do not 
in reality suffer those changes without some previous disturbance 
in the attraction of their elements. Eremacausis always pre- 
cedes fermentation and putrefaction, and it is not until after the 
absorption of a certain quantity of oxygen that the signs of a trans- 
formation in the interior of the substances show themselves. 

It is a very general error to suppose that organic substances 
have the power of undergoing change spontaneously, without the 
aid of an external cause. When they are not already in a state 
of change, it is necessary, before they can assume that state, that 
the existing equilibrium of their elements should be disturbed ; 
and the most common cause of this disturbance is undoubtedly 
the atmosphere which surrounds all bodies. 

The juices of the fruit or other parts of a plant prone to de- 
composition, retain their properties unchanged as long as they 
are protected from immediate contact with the air, that is, as 
long as the cells or organs in which they are contained resist the 
iufluence of the air. It is not until after the juices have been 
exposed to the air, and have absorbed a certain quantity of 
oxygen, that the substances dissolved in them begin to be decom- 
posed. 

The beautiful experiments of Gay-Lussac upon the fermenta- 
tion of the juice of graphs, as well as the important praclicjtl 
improvements to which they have led, are the best proofs that the 
atmosphere possesses an influence upon the changes of organic 
substances. Tlie juice of grapes expressed under a receiver 



OF BODIES DESTITUTE OF NITROGEN. 308 

filled with mercury, so that air was completely excluded, did not 
ferment. But when the smallest portion of air was introduced, 
a certain quantity of oxygen became absorbed, and fermentation 
immediately began. Although the juice was expressed from the 
grapes in contact with air, under the conditions therefore neces- 
sary to cause its fermentation, still this change did not ensue 
when the juice was heated in close vessels to the temperature of 
boiling water. When thus treated, it could be preserved for 
^lears without losing its property of fermenting. A fresh expo- 
sure to the air at any period caused it to ferment. 

Animal food of every kind, and even the most delicate vege- 
tables, may be preserved unchanged if heated to the temperature 
of boiling water in vessels from which the air is completely ex- 
cluded. Food thus prepared has been kept for fifteen years, and 
upon opening the vessels after this long time, has been found as 
fresh and well-flavored as when originally placed in them. 

The action of the oxygen in these processes of decomposition 
is very simple ; it excites changes in the composition of the 
azotized matters dissolved in the juices ; — the mode of combina- 
tion of the elements of those matters undergoes a disturbance 
and change in consequence of their contact with oxygen. The 
oxygen acts here in a similar manner to the friction or motion 
which effects the#mutual decomposition of two salts, the crystalli- 
zation of salts from their solution, or the explosion of fulminating 
mercury. It causes the state of rest to be CA^nverted into a state 
of motion. 

When this condition of intestine motion is once excited, the 
presence of oxygen is no longer necessary. The smallest parti- 
cle of an azotized body in this act of decomposition exercises an 
influence upon the particles in contact with it, and the state of 
motion is thus propagated through the substance. The air may 
now be completely excluded, but the fermentation or putrefaction 
proceeds uninterruptedly to its completion. 

Aldehyde attracts oxygen from the air, and, by the process of 
eremacausis, becomes vinegar ; if the air be now excluded, the 
disturbance already begun is not arrested, but the products are 
very different. Two substances are then formed by a change in 



304 EREMACAUSIS OR DECAY 

the arrangement of the elements. Their composition is similar, 
but they are very unlike in character. 

The contact of ammonia and of alkalies in general may be 
mentioned among the chemical conditions which determine the 
commencement of eremacausis ; for their presence causes manv 
substances to absorb oxygen and to decay, in which neither 
oxygen nor alkalies alone produce that change. 

Thus alcohol does not combine with the oxygen of the air a. 
common temperatures. But a solution of potash in alcohol ab 
sorbs oxygen with much rapidity, and acquires a brown color. 
The alcohol is found after a short time to contain acetic acid, 
formic acid, and the products of the decomposition of aldehyde 
by alkalies, including the resin of aldehyde, which gives the 
liquid a brown color. 

The most general condition for the production of eremacausis 
in organic matter is contact with a body already in the state of 
eremacausis or putrefaction. We have here an instance of true 
contagion ; for the communication of the state of combustion is 
in reality the effect of the contact. 

It is decaying wood which causes fresh wood around it to as- 
sume the same condition, and it is the very finely divided woody 
fibre in the act of decay which in moistened gall-nuts converts 
the tannic acid with such rapidity into gallic acid. 

A most remarkable and decided example of this induction of 
combustion has been observed by De Saussure. It has already 
been mentioned, that moist woody fibre, cotton, silk, or vegetable 
mould, in the act of fermentation or eremacausis, converts the 
oxygen gas surrounding it into carbonic acid, without changt of 
volume. Now. De Saussure added a certain quantity of hydro- 
gen gas to the oxygen, and observed a diminution in volume 
immediately after the addition. A part of the hydrogen gas had 
disappeared, and along with it a portion of the oxygen, but a cor- 
responding quantity of carbonic acid gas had not been formed. 
The hydrogen and oxygen had disappeared in exactly the 
same proportion as that in which they combine to form water ; 
a true combustion of the hydrogen, therefore, had been induced 
by mere contact with matter in the state of eremacausis. The 
action of the decaying substance here produced results exactly 



OF BODIES DESTITUTE OF NITROGEN. 305 



similar to those effected by spongy platinum ; but that they pro- 
ceeded from a different cause was shown by tlie fact that the 
presence of carbonic oxide, which arrests completely the action 
of platinum on a mixture of oxygen and hydrogen, did not re- 
tard in the slightest degree the combustion of the hydrogen in 
contact with the decaying bodies. 

But tlie same bodies were found by De Saussure not to pos- 
sess the property just described, before they were in a state of 
fermentation or decay ; and he has shown that even when they 
are in this state, the presence of antiseptic matter destroys com- 
pletely all their influence. 

Let us suppose a volatile substance containing a large quanti- 
ty of hydrogen to be substituted for the hydrogen gas in De 
Saussure's experiments. Now, the hydrogen in such compounds 
being contained in a state of greater condensation would suffer 
a more rapid oxidation, that is, its combustion would be sooner 
completed. This principle is in reality attended to in the manu- 
factories in which acetic acid is prepared according to the new 
plan. In the process there adopted all the conditions are afforded 
for the eremacausis of alcohol, and for its consequent conversion 
into acetic acid. 

The alcohol is exposed to a moderate heat, and spread over a 
very extended surface, but these conditions are not sufficient to 
effect its oxidation. The alcohol must either be in contact with 
decaying wood, or must contain a substance which is with facility 
changed by the oxygen of the air, and either enters into erema- 
causis by mere contact with oxygen, or by its fermentation or 
putrefaction yields products possessed of this property. A small 
quantity of beer, acescent wine, a decoction of malt, honey, and 
numerous other substances of this kind, possess the action 
desired. 

The difference in the nature of the substances possessing this 
property shows, tliat none of them can contain a peculiar matter 
which has the property of exciting eremacausis ; they are only 
the bearers of an action, the influence of which extend-s beyond 
the sphere of their own attractions. Their power consists in a 
condition of decomposition or eremacausis, which impresses the 
same condition upon the atoms of alcohol in its vicinity ; exactly 



306 EREMACAUSIS OR DECAY 

as in the case of an alloy of platinum and silver dissolving in 
nitric acid, in which the platinum becomes oxidized by virtue of 
an inductive action exercised upon it by the silver in the act of 
its oxidation. In the preparation of vinegar, the hydrogen of 
alcohol, with the formation of water and evolution of heat, is 
oxidized at the expense of the oxygen in contact with it ; the 
residue is aldehyde, a substance possessing as great an allinity 
for oxygen as sulphurous acid, and by uniting directly with the 
latter, it produces acetic acid. 



OF BODIES CONTAINING NITROGEN. 30" 



CHAPTER VIII. 

Eremacausis of Substances containing Nitrogen : Nitrification. 

When azotized substances are burned at high temperatures, theii 
nitrogen does not enter into direct combination with oxygen. 
The knowledge of this fact is of assistance in considering the 
process of the eremacausis of such substances. Azotized organic 
matter always contains carbon and hydrogen, both of which 
elements have a very strong affinity for oxygen. 

Now nitrogen possesses a very feeble affinity for oxygen, so 
that it is placed, in regard to that element, in a position similai 
to that of the carbon of bodies containing much hydrogen during 
their combustion ; a separation of the carbon of the latter sub- 
stances in an uncombined state takes place, and in the same way 
the substances containing nitrogen give out that element in its 
gaseous form. 

When moist azotized animal matter is exposed to the action 
of air, ammonia is constantly liberated ; nitric acid is never 
formed under these circumstances. 

But when alkalies or alkaline bases are present, a union of 
oxygen with the nitrogen takes place under the same circum- 
stances, and nitrates are formed together with the other products 
of oxidation. 

Although we see the most simple means and direct methods 
employed in the great processes of decomposition occurring in 
nature, still we find that the final result depends on a succession 
of actions, which are essentially influenced by the chemical 
nature of the bodies submitted to decomposition. 

When it is ol)served that the character of a substance remains 
unaltered in a whole series of phenomena, there is no reason to 



308 EREMACAUSIS OR DECAY 

ascribe a new character to it, for the purpose of explaining a sin. 
gle phenomenon, especially where the explanation of that, 
according to known facts, offers no difficulty. 

The most distinguished philosophers suppose that the nitrogen 
in an animal substance, when exposed to the action of air, 
water, and alkaline bases, possesses the power of combining 
directly with oxygen, and of thus forming nitric acid ; but we 
are not acquainted with a single fact which justifies this opinion. 
It is only by the interposition of a large excess of hydrogen in 
the state of combustion or oxidation, that nitrogen can be eon- 
verted into an oxide. ^ 

When a compound of nitrogen and carbon, such as cyanogen. 
is burned in oxygen gas, its carbon alone is oxidized ; and when 
it is conducted over a metallic oxide heated to redness, an oxide 
of nitrogen is very rarely produced, and never when the carbon 
is in excess. Kuhlmann found in his experiments, that it was 
only when cyanogen was mixed with an excess of oxygen gas 
and conducted over spongy platinum, that nitric acid was gene 
rated. 

Kuhlmann could not succeed in causing pure nitrogen to com- 
bine directly with oxygen, even under the most favorable cir- 
stances ; thus, with the aid of spongy platinum at different tem- 
peratures, no union took place. 

The carbon in the cyanogen gas must, therefore, have given 
rise to the combustion of the nitrogen by induction. 

On the other hand, we find that ammonia (a compound of hy- 
drogen and nitrogen) cannot be exposed to the action of oxygen, 
without the formation of an oxide of nitrogen, and production of 
nitric acid, in consequence of this union. 

It is owing to the great facility with which ammonia is 
converted into nitric acid, that it is so difficult to obtain a cor- 
rect determination of the quantity of nitrogen in a compound 
subjected to analysis, in which it is either contained in the form 
of ammonia, or from which ammonia is formed by an elevation 
of temperature. For when ammonia is passed over the red-hol 
oxide of copper, it is converted, either completely or ])artiallyi 
into binoxide of nitrogen. 

When ammoniacal gas is conducted over peroxide of manga. 



OF BODIES CONTAINING NITROGEN. 309 

fiese or iron heated to redness, a large quantity of nitrate of am. 
monia is obtained, if the ammonia be in excess ; and the same 
decomposition happens when ammonia and oxygen are together 
passed over red-hot spongy platinum. 

It appears, therefore, that the combination of oxygen with 
nitrogen occurs rarely during the combustion of compounds of 
the latter element with carbon, but that nitric acid is always a 
product when ammonia is present in the substance exposed to 
oxidation. 

The cause wherefore the nitrogen in ammonia exhibits such 
a strong disposition to become converted into nitric acid is un- 
doubtedly that the two products, which are the result of the oxi- 
dation of the constituents of ammonia, possess the power of unit- 
ing with one another. Now this is not the case in the combus- 
tion of compounds of carbon and nitrogen ; here one of the pro- 
ducts is carbonic acid, which, on account of its gaseous form, 
must oppose the combination of the oxygen and nitrogen, by 
preventing their mutual contact, while the superior affinity of its 
carbon for the oxygen during the act of its formation will aid 
this effect. 

When sufficient access of air is admitted during the combus- 
tion of ammonia, water is formed as well as nitric acid, and both 
of these bodies combine together. The presence of water may, 
indeed, be considered as one of the conditions essential to nitrifi- 
cation, since nitric cannot exist without it. 

Eremacausis is a kind of putrefaction, differing from the com- 
mon process of putrefaction, only in the part which the oxygen 
of the air plays in the transformations of the body in decay. 
When this is remembered, and when it is considered that in the 
transposition of the elements of azotized bodies their nitrogen 
always assumes the form of ammonia, and that in this form nitro- 
a^en possesses a much greater disposition to unite with oxygen 
than it has in any of its other compounds ; we can with difficulty 
resist the conclusion, that ammonia is the source of the formation 
of nitric acid on the surface of the earth. 

Azotized animal matter is not, therefore, the immediate cause 
of nitrification ; it contributes to the production of nitric acid 



510 EREMACAUSIS OR DECAY. 

only in so far as it is a slow and continued source of am. 
monia.* 

Now it has been shown in the former part of this work, thai 
ammonia is always present in the atmosphere, so that nitrates 
might thence be formed in substances which themselves con- 
tained no azotized matter. It is known also, that porous sub- 
stances possess generally the power of condensing ammonia ; 
there are few ores of iron which do not evolve ammoniacal pro- 
ducts when heated to redness, and ammonia is the cause of the 
peculiar smell perceived upon moistening aluminous minerals. 
Thus, ammonia, by being a constituent of the atmosphere, is a 
very widely diffused cause of niti'ification, which will come into 
play whenever the different conditions necessary for the oxida- 
tion of ammonia are combined. It is probable that other orga- 
nic bodies in the state of eremacausis are the means of causing 
the combustion of ammonia ; at all events, the cases are very 
rare in which nitric acid is generated from ammonia, in the ab- 
sence of all matter capable of eremacausis. 

From the preceding observations on the causes of fermenta- 
tion, putrefaction, and decay, we may now draw several conclu- 
sions calculated to correct the views generally entertained re- 
specting the fermentation of wine and beer, and several other 
important processes of decomposition occurring in nature. 

* According to the observations of Collard de Martigny, ammonia is 
converted directly into nitric acid when in contact with hydrate of lime 
and with air, without the intervention of any decaying substance. 



YEAST FROM BEER AND WINE. 311 



CHAPTER IX. 

On Vinous Fermentation : — Wine and Beer. 

It has already been mentioned that fermentation is excited in the 
juice of grapes by the access of air ; alcohol and carbonic acid 
being formed by the decomposition of the sugar contained in the 
fluid. But it was also stated, that the process once commenced, 
continues until all the sugar is completely decomposed, quite 
independently of any further influence of the air. 

In addition to the alcohol and carbonic acid formed by the fer- 
mentation of the juice, there is also produced a yellow or grey 
insoluble substance, containing a large quantity of nitrogen. It 
is this body which possesses the power of inducing fermentation 
in a new solution of sugar, and which has in consequence re- 
ceived the name o^ ferment. 

The alcohol and carbonic acid are produced from the elements 
of the sugar, and the ferment from those azotized constituents of 
the juice termed gluten or vegetable albumen. 

According to the experiments of De Saussure, fresh impure 
gluten evolved, in five weeks, twenty-eight times its volume of a 
gas which consisted of f of carbonic acid, and J of pure hydro- 
gen gas ; ammoniacal salts of several organic acids were formed 
at the same time. Water must, therefore, be decomposed during 
the putrefaction of gluten ; the oxygen of this water must enter 
into combination with some of its constituents, whilst hydrogen 
is liberated, a circumstance which happens only in decomposi- 
tions of the most energetic kind. Neither ferment, nor any 
substance similar to it, is formed in this case ; and we have seen 
that hydrogen is not evolved in the fermentation of saccharine 
vegetable juices. 

It is evident that the decomposition which gluten suffers in an 
isolated state, and that which it undergoes when dissolved in a 



312 VINOUS FERMENTATION 

vegetable juice, belong to two different kinds of transformations. 
There is reason to believe that its change to the insoluble state 
depends upon an absorption of oxygen, for its separation in this 
state may be effected, under certain conditions, by free exposure 
to the air, without the presence of fermenting sugar. It is i<nown 
also that the juice of grapes, or vegetable juices in general, be- 
come turbid when in contact with air, before fermentation com- 
mences ; and this turbidity is owing to the formation of an 
insoluble precipitate of the same nature as ferment. 

From the phenomena observed during the fermentation of wort,* 
it is known with perfect certainty that ferment is formed fj'om 
gluten at the same time that the transformation of the sugar is 
effected ; for the wort contains the azotized matter of the corn, 
namely, gluten in the same condition as it exists in the juice of 
grapes. The wort ferments by the addition of yeast, but after its 
decomposition is completed, the quantity of ferment or yeast is 
found to be thirty times greater than it originally was. 

Yeast from beer and that from wine, examined under the mi- 
croscope, present the same form and general appearance. They 
are both acted on in the same manner by alkalies and by acids, 
and possess the power of inducing fermentation anew in a solution 
of sugar; in short, they must be considered as identical. 

The fact that water is decomposed during the putrefaction of 
gluten, has been completely proved. The tendency of the carbon 
of the gluten to appropriate the oxygen of water must therefore 
always be in action, whether the gluten is decomposed in a soluble 
or insoluble state. These considerations, therefore, as well as 
the circumstance which all the experiments made on this subject 
appear to point out, that the conversion of gluten to the insoluble 
state is the result of oxidation, lead us to conclude that tlie oxy- 
gen consumed in this process is derived from the elements of 
water, or from the sugar which contains oxygen and hydrogen in 
the same proportion as water. At all events, the oxygen thus 
consumed in the fermentation of wine and beer is not taken from 
the atmosphere. 



• Wort is an infusion of malt; it consists of the soluble parts of th.isi 
•ubstance dissolved in water. 



OILY AND ETHEREAL PRODUCTS. 313 

The fermentation of pure sugar in contact with yeast must evi- 
dently be a very different process from the fermentation of wort 
or of must* 

In the former case, the yeast disappears during the decompo- 
sition of sugar ; but in the latter, a transformation of gluten 
is effected at the same time, by which ferment is generated. 
Thus yeast is destroyed in the one case, but is formed in the 
other. 

Now, since no free hydrogen gas can be detected during the 
fermentation of beer and wine, it is evident that, since the oxida- 
tion of the gluten, that is, its conversion into ferment, must take 
place at the cost either of the oxygen of the water, or of that of 
the sugar; either the hydrogen liberated must enter into new 
combinations, or by the deoxidation of the sugar, new compounds 
containing a large proportion of hydrogen, and small quantity of 
oxygen, together with the carbon of the sugar, must be formed. 

It is well known that wine and fermented liquors generally 
contain, in addition to the alcohol, other substances which could 
not be detected before their fermentation, and which must have 
been formed, therefore, during that process, in a manner similar 
to the production of mannite. The smell and taste distinguishing 
wine from all other fermented liquids are known to depend upon 
an ether of a volatile and highly combustible acid ; the ether is 
of an oily nature, and has received the name CEnanthic ether. 
It is also ascertained that the smell and taste of brandy from corn 
and potatoe are owing to a peculiar oil, the oil of potatoe spirit 
This oil is more closely allied to alcohol in its properties, than to 
any other organic substance. 

These bodies are products of the deoxidation of the substances 
dissolved in the fermenting liquids ; they contain less oxygen 
than sugar or gluten, but are remarkable for their large propor- 
tion of hydrogen. 

CEnanthic acid contains an equal number of equivalents of 
carbon and hydrogen, exactly the same proportions of these 
elements, therefore, as sugar, but by no means the same pro- 
portion of oxygen. The oil of potatoes contains much more 
hydrogen. 

* The liquid expressed from grape* when fuUy ripe is ooJ ed muai. 
16 



314 VINOUS FERMENTATION. 

Although it cannot be doubted that these volatile liquids are 
formed by a mutual interchange of the elements of gluten and of 
sugar, in consequence, therefore, of a true process of putrefac- 
tion, still it is certain, that other causes exercise an influence 
upon their production and peculiarities. 

The substances in wine to which its taste and smell are owing; 
are generated during the fermentation of the juice of such grapes 
as contain a certain quantity of tartaric acid ; they are not found 
in wines free from all acid, or which contain a different organic 
acid, such as acetic acid. 

The wines of warm climates possess no odor ; wines grown in 
France have it in a marked degree, but in the v/ines from the 
Rhine the perfume is most intense. The kinds of grapes on tlw3 
Rhine, which ripen very late, and scarcely ever completely, such 
as the RiESSLiNG and Orleans, have the strongest perfume or 
bouquet, and contain, proportionally, a larger quantity of tartaric 
acid. The wines from the earlier grapes, such as the Ru- 
LANDER, and others, contain a large proportion of alcohol, and 
are similar to Spanish wines in their flavor, but they possess no 
bouquet. 

The grapes grown at the Cape from Riesslings, transplanted 
from the Rhine, produce an excellent wine, which does not, how- 
ever, possess the aroma peculiar, to the Rhenish wine. 

It is evident, from these facts, that the acid of wines, and their 
characteristic perfumes, have some connexion, for they are al- 
ways found together ; and it can scarcely be doubted that the 
presence of the former exercises a certain influence on the for- 
mation of the latter. This influence is very plainly observed in 
the fermentation of liquids destitute of tartaric acid, and particu- 
larly of those which are nearly neutral or alkalinp, such as the 
mash* of potatoes or corn. 

The brandy obtained from corn and potatoes contains an 
ethereal oil of a similar composition in both, to which these li- 
quors owe their peculiar smell. This oil is generated during the 
fermentation of the mash ; it exists ready formed in the fer- 

• Mash is the mixture of malt, potatoes, and water, in the math tuitt a 
laige vessel in which it is infused. 



ODORIFEROUS PRODUCTS. 315 

merited liquids, and distils over with alcohol when a gentle heai 
is applied. 

It is observed that a greater quantity of alcohol is obtained 
when the mash is made quite neutral by ashes or by carbonate 
of lime, and that the proportion of oil in the brandy also is in- 
creased. 

Now, it is known that brandy made from potatoe starch, which 
has been converted into sugar by dilute sulphuric acid, is com- 
pletely free from the potatoe oil, so that this substance must be 
generated in consequence of a change suffered by the cellular 
tissue of the potatoes during their fermentation. 

Experience has shown that the simultaneous fermentation or 
putrefaction of the cellular tissue, by which this oil is gene- 
rated, may be completely prevented in the fabrication of brandy 
from corn. 

The same malt, which in the preparation of brandy yields a 
fluid containiHg the oil of which we are speaking, affords, in the 
formation of beer, a spirituous liquor in which no trace of that oil 
can be detected. The principal difference in the preparation of 
the two liquids is, that in the fermentation of wchI, an aromatic 
substance (hops) is added, and it is certain that its presence 
modifies the transformations which take place. Now, it is known 
that the volatile oil of mustard, and the empyreumatic oils, arrest 
completely the action of yeast ; and although the oil of hops does 
not possess this property, still it diminishes, in a great degree, the 
influence of decomposing azotized bodies upon the conversion of 
alcohol into acetic acid. There is, therefore, reason to believe 
that some aromatic substances, when added to fermenting mix- 
tures, are capable of producing very various modifications in the 
nature of the prod-ucts generated. 

Whatever opinion, however, may be held regarding the origin 
of the volatile odoriferous substances obtained in the fermenta- 
tion of wine, it is quite certain that the characteristic smell of 



* In the manufactory of M. Dubrunfaut, so considerable a quantity of thi» 
oil is obtained under certain circumstances from brandy made from potatoes 
that it in'ght be employed for the purpose of illuminating his whole manu 
factory. 



S16 VINOUS FERMENTATION. 

wine is owing to an ether of an organic acid, resembling one of 
the fatty acids (oenanthic ether). 

It is only in liquids containing other very soluble acids, that 
the fatty acids and oenanthic acid are capable of entering into 
combination with the ether of alcohol, and of thus producing 
compounds of a peculiar smell. This ether is found in all wines 
containing a free acid, but is absent from those in which no acids 
are present. This acid, therefore, is the means by which the 
smell is produced ; since without its presence ounanthic ether 
could not be formed. 

The greatest part of the oil of brandy made from corn con- 
sists of a fatty acid not converted into ether; it dissolves oxide 
of copper and metallic oxides in general, and combinee with the 
alkalies. 

The principal constituent of this oil is an acid identical in 
composition with oenanthic acid, but different in properties. 
(Mulder.) It is formed in fermenting liquids, which, if they be 
acid, contain only acetic acid, a body which has no influence in 
causing other acids to form ethers. 

The oil of brandy made from potatoes is the hydrate of an 
organic base analogous to ether, and capable, therefore, of enter- 
ing into combination with acids. It is formed in considerable 
quantity in fermenting liquids possessing an alkaline reaction ; 
under circumstances, consequently, in which it is incapable of 
combining with an acid. 

The products of the fermentation and putrefaction of neutral 
vegetable and animal matters are generally accompanied by 
substances of an offensive odor ; bu; tbs most remarkable exam- 
ple of the generation of a true ethereal oil is seen in the fermen- 
tation of the Centmirium minus, a plant destitute of smell. When 
it is exposed in water to a sUghtly elevated temperature it fer- 
ments, and emits an agreeable penetrating odor. By the distil- 
lation of the liquid, an ethereal oily substance of great volatility 
is obtained, which excites a pricking sensation in the eyes, and 
a flow of tears (Biichner). 

We know that most of the blossoms and vegetable substances 
possessing a smell owe this property to a volatile oil existing in 



THE BAVARIAN PROCPJSS. SP 

them ; but it is not less certain, that others emit a smell only 
when they undergo change or decomposition. 

Arsenic and arsenious acid are both quite inodorous. It is only 
during their oxidation that they emit their characteristic odor of 
garlic. The oil of the berries of the elder-ti'ee, many kinds of 
oil of turpentine, and oil of lemons, possess a smell only during 
their oxidation or decay. The same is the case with many 
blossoms ; and Geiger has shown, that the smell of musk is 
owing to its gradual putrefaction and decay. 

It is also probable, that the peculiar odorous principle of many 
vegetable substances is newly formed during the fermentation of 
the saccharine juices of the plants. At all events, it is a fact, 
that very small quantities of the blossoms of the violet, elder, 
linden, or cowslip, added to a fermenting liquid, are sufficient to 
communicate a very strong taste and smell, which the addition 
of the water distilled from a quantity a hundred times greater 
would not effect. The various kinds of beer manufactured in 
Bavaria are distinguished by different flavors, which are given 
by allowing small quantities of the herbs and blossoms of particu- 
lar plants to ferment along with the wort. On the Rhine, also, 
an artificial houquet is often given to wine for fraudulent pur. 
poses, by the addition of several species of the sage and rue to 
the fermenting liquor ; but the fictitious perfume thus obtained 
differs from the genuine aroma, by its inferior durability, and by 
being gradually dissipated. 

The juice of grapes grown in different climates differs not only 
in its proportion of free acid, but also in respect of the quantity of 
sugar dissolved in it. The quantity of azotized matter in the juice 
seems to be the same in whatever part the grapes may grow ; at 
least, no difference has been observed in the amount of yeast 
formed during fermentation in the south of France, and on the 
Rhine. 

The grapes grown in hot climates, as well as the boiled juice 
obtained fi-oui them, are proportionally rich in sugar. Hence, 
during the fermentation of the juice the complete decomposition 
of its azotized matters, and their separation in the insoluble state, 
are effected before all the sugar has been converted into alcohol and 
carbonic acid. A certain quantity of the sugar consequently 



318 VINOUS FERMENTATION. 

remains mixed with the wine in an undecomposed state, the con- 
dition necessary for its further decomposition being absent. 

The azotized matters in the juice of grapes of the temperate 
zones, on the contrary, are not completely separated in the 
insoluble state, when the entire transformation of the sugar is 
effected. The wine of these grapes, therefore, does not contain 
sugar, but variable quantities of undecomposed gluten in solu- 
tion. 

This gluten gives the wine the property of becoming spon- 

taneously converted into vinegar, when the access of air is not 

(J prevented. For it absorbs oxygen and becomes insoluble ; and 

its oxidation is communicated to the alcohol, which is converted 

into acetic acid. 

By allowing the wine to remain at rest in casks with a very 
limited access of air, and at the lowest possible temperature, the 
oxidation of this azotized matter is effected without the alcohol 
undergoing the same change, a higher temperature being neces- 
sary to enable alcohol to combine with oxygen. As long as the 
wine in the stilling-casks deposits yeast, it can still be caused to 
ferment by the addition of sugar, but old well -cleared wine has 
lost this property, because the condition necessary for fermenta- 
tion, namely, a substance in the act of decomposition or putre- 
faction, is no longer present in it. 

In hotels and other places where Wine containing much gluten 
is drawn gradually from a cask, and a proportional quantity of 
air necessarily introduced, its eremacausis, that is, its conversion 
into acetic acid, is prevented by the addition of a small quantity 
of sulphurous acid. This acid, by entering into combination with 
the oxygen ot the air contained in the cask, or dissolved in the 
wine, prevents the oxidation of the organic matter. 

The various kinds of beer differ from one another in the same 
way as the wines. 

English, French, and most of the German beers, are converted 
into vinegar when exposed to the action of air. But this pro- 
perty IS not possessed by Bavai'ian beer, which may be kept in 
vesSfds only half-filled without acidifying or experiencing any 
change. This valuable quality is obtained for it by a peculiar 
management of the fermentation of the wort. The perfection of 



THE BAVARIAN PROCESS. 318 

experimental knowledge has here led to the solution of one of the 
most beautiful problems of the theory of fermentation. 

Wort is proportionally richer in gluten than in sugar, so that, 
during its fermentation in the common way, a great c^uantity of 
yeast is formed as a thick scum. The carbonic acid evolved 
during the process attaches itself to the particles of the yeast, 
by which they become specifically lighter than the liquid 
in which they are formed, and rise to its surface. Gluten, in the 
act of oxidation, comes in contact with the particles of the decom- 
posing sugar in the interior of the liquid. The carbonic acid 
from the sugar and insoluble ferment from the gluten are disi- 
engaged simultaneously, and cohere together. 

A great quantity of gluten remains dissolved in the fermented 
liquid, even after the transformation of the sugar is completed, 
and this gluten causes the conversion of the alcohol into acetic 
acid, on account of its strong disposition to attract oxygen, and to 
undergo decay. Now, it is plain, that with its separation, and 
that of all substances capable of attracting oxygen, the beer 
would lose the property of becoming acid. This end is com- 
pletely attained in the process of fermentation adopted in 
Bavaria. 

The wort, after having been treated with hops in the usual 
manner, is thrown into very wide flat vessels, in which a large 
surface of the liquid is exposed to the air. The fermentation is 
then allowed to proceed, while the temperature of the chambers 
in which the vessels are placed is never allowed to rise above 
from 45° to 50° F. The fermentation lasts from three to six 
weeks, and the carbonic acid evolved during its continuance is 
not in large bubbles which burst upon the surface of the liquid, 
but in small bubbles like those which escape from an acidulous 
mineral water, or from a liquid saturated by high pressure. The 
surface of the wort is scarcely covered with a scum, and all the 
yeast is deposited on the bottom of the vessel, in the form of a 
fine viscous slime. 

In order to obtain a clear conception of the great difference 
Detween the two kinds of fermentation, it may perhaps be 
sufiicif Tit to recall to mind the fact, that the transformation of 
gluten or of other azotized matters is a process consisting of 



320 FERMENTATION OF BEER 

Beveral stages. The first stage is the conversion of (he gluten 
into insoluble ferment in the interior of the liquid, and as the 
transformation of the sugar goes on at the same time, carbonic 
acid and yeast are simultaneously disengaged. It is known with 
certainty, that this formation of yeast depends upon oxygen 
being appropriated by the gluten in the act of decomposition ; 
but it has not been sufficiently shown, whether this oxygen is 
derived from the water, from the sugar, or from the gluten 
itself; whether it combines directly with the gluten, or merely 
■|M'ith its hydrogen, so as to form water. For the purpose of 
^obtaining a definite idea of the process, we may designate the 
first change as the stage of oxidation. This oxidation of the 
gluten then, and the transposition of the atoms of the sugar into 
alcohol and carbonic acid, are necessarily attendant on each 
other, so that if the one is arrested the other must also cease. 

Now, the yeast which rises to the surface of the liquid is not 
the product of a complete decomposition, but is oxidized gluten 
still capable of undergoing a new transformation by the transpo- 
sition of its constituent elements. By virtue of this condition it 
has the power to excite fermentation in a solution of sugar ; and 
if the gluten be also present, the decomposing sugar induces its 
conversion into fresh yeast, so that, in a certain sense, the yeast 
appears to reproduce itself. 

Yeast of this kind is oxidized gluten in a state of putrefaction, 
and by virtue of this state it induces a similar transformation in • 
the elements of the sugar. 

The yeast formed during the fermentation of Bavarian beer 
is oxidized gluten in a state of decay. The process of decompo- 
sition which its constituents are sufTering, gives rise to a very 
protracted putrefaction ( fermentation) in the sugar. The inten- 
sity of the action is diminished in so great a degree, that the 
gluten which the fluid still holds in solution takes no part in it; 
the sugar in fermentation does not excite a similar state in the 
gluten. 

But the contact of the already decaying and precipitated 
gluten or yeast, causes the eremacausis of the gluten dissolved in 
the wort ; oxygen gas is a':)sorbed from the air, and all the gluter 
in solution is deposited as yeast. 



THE BAVARIAN PROCESS. 321 

The ordinary frothy yeast may be removed from fermenting 
beer by filtration, without the fermentation being thereby arrest- 
ed ; but the precipitated yeast of Bavarian beer cannot be 
removed without the wliole process of its fermentation being in- 
terrupted. Tlie beer ceases to ferment altogether, or, if the 
temperature is raised, undergoes the ordinary femnentation. 

The precipitated yeast does not excite oi'dinary fermentation, 
and, consequently, is quite unfitted for the purpose of baking ; 
but the common frothy yeast can cause the kind of fermentation 
by which the former kind of yeast is produced. 

When common yeast is added to wort at a temperature of 
between 40° and 50° F., a slow tranquil fermentation takes 
place, and a matter is deposited on the bottom of the vessel, 
which may be employed to excite new fermentation ; and when 
the same operation is repeated several times in succession, the 
ordinary fermentation changes into that process by which only 
precipitated yeast is formed. The yeast now deposited has lost 
the property of exciting ordinary fermentation, but it produces 
the other process even at a temperature of 50° F. 

In wort subjected to fermentation, at a low temperature, with 
this kind of yeast, the condition necessary for the transformation 
of the sugar is the presence of that yeast ; but for the conversion 
of gluten into ferment by a process of oxidation, something more 
is required. 

When the power of gluten to attract oxygen is increased by 
contact with precipitated yeast in a state of decay, the unre- 
strained access of aii is the only other condition necessary for its 
own conversion into the same state of decay, that is, for its oxida- 
tion. We have already seen that the presence of free oxygen 
and of gluten are conditions which determine the eremacausis of 
alcohol and its conversion into acetic acid, but they are inca- 
pable of exerting this influence at low temperatures. A low 
temperature retards the slow combustion of alcohol, while the 
gluten combines spontaneously with the oxygen of the air, just 
as sulphurous acid does when dissolved in water. Alcohol un- 
dergoes no such change at low temperatures, but during the oxi- 
dation of the gluten in contact with it, is placed in the same 
condition as the gluten itself when sulphurous acid is added to 
15* 



322 FERMENTATION OF BEER. 

the wine in which it is contained. The oxygen of the aii 
unites both with the gluten and alcohol of wine not treated with 
sulphurous acid ; but when this acid is present it combines with 
neither of them, being altogether absorbed by the acid. The 
same thing happens in the peculiar process of fermentation 
adopted in Bavaria. The oxygen of the air unites only with 
the gluten and not with the alcohol, although it would have 
combined with both at higher temperatures, so as to form 
acetic acid. 

Thus, then, this remarkable process of fermentation with the 
precipitation of a mucous-like ferment consists of a simultaneous 
putrefaction and decay of the same liquid. The sugar is in the 
state of putrefaction, and the gluten in that of decay. 

Appert's method of preserving food, and this kind of fermenta- 
tion of beer, depend on the same principle. 

In the fermentation of beer after this manner, all the sub- 
stances capable of decay are separated from it by means of an 
unrestrained access of air, while the temperature is kept suffi- 
ciently low to prevent the alcohol from combining with oxygen. 
The removal of these substances diminishes the tendency of the 
beer to become acescent, or, in other words, to suffer a further 
transformation. 

In Appert's mode of preserving food, oxygen is allowed to 
enter into combination with the substance of the food, at a tem- 
perature at which decay, but neither putrefaction nor fermenta- 
tion, can take place. With the subsequent exclusion of the 
oxygen and the completion of the decay, every cause which 
could effect further decomposition of the food is removed. The 
conditions for putrefaction are rendered insufficient in both 
cases ; in the one, by the removal of the substances susceptible 
)-| of decay ; in the other, by the exclusion of the oxygen which 
would effect it. 

It has been stated to be uncertain whether gluten, during its 
conversion into common yeast, that is, into the insoluble stale in 
which i'; separates from fermenting liquids, really combines 
directly with oxygen. If it does combine with oxygen, then the 
difference between gluten and ferment would be, that the latter 
would contain a larger proportion of oxygen. Now it is very 



THE BAVARIAN PROCESS. 323 

difficult to ascertain this, and even the analysis of these substances 
cannot decide the question. Let us consider, for example, the 
relations of alloxan and alloxantin* to one another. Both of 
these bodies contain the same elements as gluten, although in 
different proportions. Now they are known to be convertible 
into each other by oxygen being absorbed in the one case, and 
in the other extracted. Both are composed of absolutely the 
same elements, in equal proportions ; with the single exception, 
that alloxantin contains 1 equivalent of hydrogen more than 
alloxan. 

When alloxantin is treated with chlorine or nitric acid, it is 
converted into alloxan ; into a body, therefore, which is alloxan- 
tin minus 1 equivalent of hydrogen. If, on the other hand, a 
stream of sulphuretted hydrogen is conducted through alloxan, 
sulphur is precipitated, and alloxantin produced. It may be said 
that, in the first case, hydrogen is abstracted ; in the other, added. 
But it would be quite as simple an explanation, if we considered 
them as oxides of the same radical : the alloxan beingf regarded 
as a combination of a body composed of Cg N2 Hj Og with 2 
equivalents of water, and alloxantin as a combination of 3 atoms 
of water with a compound consisting of Cg Nj H2 O^. The 
conversion of alloxan into alloxantin would in this case result 
from its eight atoms of oxygen being reduced to seven ; while 
alloxan would be formed out of alloxantin, by its combining with 
an additional atom of oxygen. 

Now, oxides are known which combine with water, and pre- 
sent the same phenomena as alloxan and alloxantin. But com- 
pounds of hydrogen are not known to form hydrates ; and custom, 
which rejects all dissimilarity until the claim to peculiarity is 
quite proved, leads us to prefer an opinion for which there is no 
further foundation than that of analogy. The woad {Isaiis tine- 
toria) and several species of the Nerium contair/ a substance 
similar in many respects to gluten ; this is deposited as indigo 
blue, when an aqueous infusion of the dried leaves is exposed to 
the action of the air. Now it is very doubtful whether the blue 
insoluble indigo is an oxide of the colorless soluble indigo, or the 

• Compounds obtained by the action of nitric acid on uric acid. 



J24 FERMENTATION OF BEER. 

latter a combination of hydrogen with the indigo blue. Dumas 
has found the same elements in both, except that the soluble 
compound contained 1 equivalent of hydrogen more than the 
blue. 

In "'le same manner the soluble gluten may be considered a 
compound of hydrogen, which becomes ferment by losing a cer- 
tain quantity of this element when exposed to the action of the 
oxygen of the air under favorable circumstances. At all events, 
it is certain that oxygen is the cause of the insoluble condition 
of gluten ; for yeast is not deposited on keeping wine, or during 
the fermentation of Bavai'ian beer, unless oxygen has access to 
the fluid. 

Now, whatever be the form in which the oxygen unites with 
the gluten — whether it combines directly with it, or extracts a 
portion of its hydrogen, forming water — the products formed in 
the interior of the liquid, in consequence of the conversion of 
the gluten into ferment, will still be the same. Let us suppose 
that gluten is a compound of another substance with hydrogen, 
then this hydrogen must be removed during the ordinary fermen- 
tation of must and wort, by combining with oxygen, exactly as 
in the conversion of alcohol into aldehyde by eremacausis. 

In both cases the atmosphere is excluded ; the oxygen cannot, 
then, be derived from the air, neither can it be supplied by the 
elements of water, for it is impossible to suppose that the oxygen 
will separate from the hydrogen of water, for the purpose of 
uniting with the hydrogen of gluten, in order again to form 
water. The oxygen must, therefore, be obtained from the ele- 
ments of sugar, a portion of which substance must, in order to 
the formation of ferment, undergo a different decomposition fr -m 
that which produces alcohol. Hence a certain part of the sugar 
will not be converted into carbonic ai id and alcohol, but will 
yield other products containing less oxygen than sugar itself con- 
tains. These products, as has already been mentioned, are the 
cause of the great difference in the qualities of fermented liquids, 
and particularly in their quantity of alcohol. 

Must and wort do not, therefore, in ordinary fermentation, 
yield alcohol in proportion to the quantity of sugar wliich they 
hold in solution, a part of the sugar being employed in the coo- 



THE BAVARIAN PROCESS. ?a5 



version of gluten into ferment, and not in the formation of alcohol. 
But in the fermentation of Bavarian beer, all the sugar is ex- 
pended in the production of alcohol ; and this is especially the 
case whenever the transformation of the sugar is not accom- 
panied by the formation of yeast. 

It is quite certain that in the distilleries of brandy from potcitoes. 
where no yeast is formed, or only a quantity corresponding to the 
malt which has been added, the proportion of alcohol and car- 
bonic acid obtained during the fermentation of the mash cor- 
responds exactly to that of the carbon contained in the starch. 
It is also known that the volume of carbonic acid evolved during 
the fermentation of beet-roots gives no exact indication of the 
proportion of sugar contained in them, for less carbonic acid is 
obtained than the same quantity of pure sugar would yield. 

Beer obtained by the mode of fermentation adopted in Bavaria 
contains more alcohol, and possesses more intoxicating properties, 
than that made by the ordinary method of fermentation, when 
the quantities of malt used are the same. The strong taste of 
the former beer is generally ascribed to its containing carbonic 
acid in larger quantity, and in a state of more intimate combina- 
tion ; but this opinion is erroneous. Both kinds of beer are, at 
the conclusion of the fermentation, completely saturated with 
carbonic acid, the one as much as the other. Like all other 
liquids, they both must retain such a portion of the carbonic acid 
evolved as corresponds to their temperature and power of solu- 
tion, that is, to their volumes. 

The temperature of the fluid during fermentation has a very 
important influence on the quantity of alcohol generated. It has 
been mentioned, that the juice of beet-roots allowed to ferment at 
from 86° to 95° (.30° to 35° C.) does not yield alcohol ; and that 
afterwards, in the place of the sugar, mannite^ a substance inca- 
pable of fermentation, and containing less oxygen than sugar, is 
found, together with lactic acid and mucilage. The formation 
of these products diminishes in proportion as the temperature is 
lower. But in vegetable juices, containing nitrogen, it is impos- 
sible to fix a limit, where the transformation of the sugar is un- 
disturbed by a different process of decomposition 

It is known that in the fermentation of Bavarian beer the 



326 FERMENTATION OF BEER. 



action of the oxygen of the air, and the low temperature, cause 
complete transformation of the sugar into alcohol ; the cause 
which would prevent that result, namely, the attraction of the 
gluten for oxygen, by combining with which it is converted into 
ferment, being exercised on oxygen derived from without. 

The quantity of matters in the act of transformation is na- 
turally greatest at the beginning of the fermentation of must and 
wort ; and all the phenomena which accompany the process,' 
such as evolution of gas, and heat, are most distinct at that time. 
These signs of the changes proceeding in the fluid diminish 
when the greater part of the sugar has undergone decomposition ; 
but they must cease entirely before the process can be regarded 
as completed. 

The less rapid process of decomposition which succeeds the 
violent evolution of gas, continues in wine and beer until the 
sugar has completely disappeared ; and hence it is observed, 
that the specific gravity of the liquid diminishes during many 
months. This slow fermentation, in most oases, resembles the 
fermentation of Bavarian beer, the transformation of the dissolved 
sugar being in part the result of a slow and continued decomposi- 
tion of the precipitated yeast ; but a complete separation of the 
azotized substances dissolved in it cannot take place when air is 
excluded.* 

Neither alcohol alone, nor hops, no; indeed both together, pre. 
serve beer from becoming acid. The better kinds of ale and 
porter in England are protected from acidity, but at the loss of 
the interest of an immense capital. They are placed in large 
closed wooden vessels, the surfaces of which are covered with 
sand. In these they are allowed to lie for several years, so that 



* The great influence which a rational management of fermentation has 
apon the quality of beer, is well known in several of the German states. 
In the grand-duchy of Hesse, for example, a considerable premium is 
ofTered for the preparation of beer according to the Bavarian method; and 
the premium is to be adjudged to any one who can prove that the beer 
Drewed by him has lain for six months in the store-vats without becoming 
acid. Hundreds of casks of beer became changed to vinegar before an em- 
pirical knowledge of those conditions was obtained, the influence of which 
is rendered intelligible by theory 



THE BAVARIAN PROCESS. 327 

they are treated in a manner exactly similar to wine during its 
ripening. 

A gentle diffusion of air takes place through the pores of the 
wood, but the quantity of azotized substances being very great 
in proportion to the oxygen which enters, they consume it, and 
prevent its union with the alcohol. But the beer treated in this 
way does not keep for two months without acidifying, if it be 
placed Li smaller vessels, to which free access of the air is 
permitted. 



S93 FERMENTATION ASCRIBED TO THE 



CHAPTER X. 

Fermentation ascribed to the Growth of Fungi and of Infuaoria. 

The microscopical examination of vegetable and animal mat- 
ter, in the act of fermentation or putrefaction, has lately given 
rise to the opinion, that these actions themselves, and the changes 
suffered by the bodies subjected to them, are produced in conse- 
quence of the development of fungi, or of microscopical animals, 
the germs or eggs of which are supposed to be diffused every- 
where, in a manner inappreciable to our senses ; they are sup- 
posed to be developed when they meet with a medium fitted to 
afford them nourishment. 

Several philosophers have ascribed to this circumstance the 
fermentation of wort, and of the juice of the grape. They assert, 
that the decomposition of sugar into alcohol and carbonic acid is 
effected by the contact of particles of the sugar with the growing 
plants, which they view as the yeast, or ferment, without study- 
ing more closely the final causes of the decomposition of the 
sugar. It has been supposed that this view is opposed to the 
theory detailed in the preceding pages, which described contact 
as the cause of a peculiar activity or power. 

In all chemical processes, and in all changes effected by 
chemical affinity, we observe that contact is essential for the ex- 
ercise of the acting power. Hence, chemists describe affinity as 
a force distinct from other powers, because it acts only in imme- 
diate contact, or at inappreciable distances. Thus contact plays 
an important part in every case of combination or decomposition, 
for without contact these changes would not take place. In this 
sense, all substances effecting combination or decomposition are 
bodies acting by contact. 

In the theory of fermentation alluded to, it was not asserted 
that the yeast or ferment could effect the decomposition of sugar 



GROWTH OF FUNGI AND OF INFUSORIA. 329 



at appreciable distances. In this respect, therefore, the two 
theories are not opposed to each other. They deviate, however, 
in this, that the one theory considers yeast as a body, the smallest 
particles of which are in a state of motion and transposition, and 
that, by virtue of this state, the particles of sugar in contact with 
it are thrown into the same state of change , while the other 
theory asserts, that the particles of yeast are little fungi, which 
are developed from germs or seeds falling into the fermenting 
liquid from the air; and that in this they grow at the expense of 
the substances containing nitrogen, which are thus converted into, 
and separated as, fungi. The particles of sugar in contact with 
the fungi are supposed to be converted into carbonic acid and 
alcohol, which, in other words, signifies, that the act of vegetation 
effects a disturbance in the chemical attractions of the elements 
of the sugar, in consequence of which they arrange themselves 
into new compounds. 

Gay-Lussac showed by experiments that the juice of grapes 
expressed apart from air, under a bell-jar full of mercury, did 
not enter into putrefaction, although it did so in the course of a 
few hours when air was admitted. The same chemist also showed, 
that fermentation immediately commences on the introduction of 
oxygen gas, of which a quantity is absorbed equal only to the 
-j^th part of the volume of carbonic acid evolved during the 
fermentation. It scarcely can be supposed, that the germs oi 
fungi exist in chlorate of potash or black oxide of manganese, out 
of which the oxygen was obtained ; and hence it is difficult 
to ascribe to a growing vegetation the causes of the decom- 
position. 

Gay-Lussac further showed, that the juice entered into fer- 
mentation on being connected with the wires of a galvanic battery,, 
under circumstances, therefore, which quite excluded theintro-j/ 
duction of every foreign body. Hence the view, that the fer- 
mentation of sugar is effected by contact with growing plants, 
must presuppose that living beings, plants for example, may be 
formed and developed without germs or seeds — a circumstance 
in direct contradiction to all observation regarding tlic growth 
af plants. 

It is certain that sponges and fungi, growing in places from 



330 FERMENTATION ASCRIBED TO THE 

which light is quite excluded, follow laws of nutrition different 
from those governing green plants ; and it cannot be doubted that 
th'iir nourishment is derived from putrefying bodies, or from the 
products of their putrefaction, which pass directly into this kind 
of plants, and obtain an organized form by the vital powers re- 
siding within them. During their growth they constantly emit 
carbonic acid, increasing in weight at the same time, while all 
other plants, under similar circumstances, would decrease in 
weight. Hence it is possible, and indeed probable, that fungi 
may have the power of growing in fermenting and putrefying 
substances, in as far as the products arising from the putrefaction 
are adapted for their nourishment. When a quantity of fungi are 
exposed to the temperature of boiling water, their vitality and 
power of germinating become completely destroyed. If they be 
now kept at a proper temperature, an evolution of gas proceeds 
in the mass thus treated ; they pass over into putrefaction, and, 
if air be admitted, into decay ; and at last nothing remains ex- 
cept their inorganic elements. The putrefaction in this case 
cannot be viewed as the act of the formation of organic beings, 
but as the act of the passage of their elements into inorganic 
compounds. 

Observations of another kind — for example, that flesh and other 
animal bodies may be kept for several weeks without putrefying, 
if placed in a vessel containing air previously heated to redness 
— have gone far to support the opinion that the process of putre- 
faction is effected by the growth of organic beings ; but all such 
experiments are of very subordinate value in support of these 
conclusions. In some experiments instituted by the author, for 
the purpose of detecting quinine in the urine of a patient in the 
habit of taking this medicine, he obtained the remarkable result, 
that this urine kept for several weeks without passing into com- 
plete putrefaction, although the urea of urine, under ordinary 
circumstances, is often completely converted into carbonate of 
ammonia in tlie space of six or eight hours. In the present case, 
the urine effervesced only siightly with acids after fourteen dayss. 
This seemed to give sufficient foundation for the opinion that the 
quinine must be the cause of this delay in the putrefaction. But 
further experiments proved that common urine introduced whea 



GROWTH OF FUNGI AND OF INFUSORIA. 331 



freohly drawn into perfectly pure vessels behaved in an exactly 
similar manner. When a little putrefying urine was added tc 
the fresh urine, the putrefaction of the latter was accelerated in 
a hi-n iegree. Wood, in which urine had been retained, ex- 
erted this action in a very decided manner, and the white, or 
yellowish-white deposit from putrefying urine (which does not 
possess an organized form) effects the conversion of urea into 
carl>onate of ammonia in the course of a few hours. 

Fresh flesh remains for several weeks without experiencing 
appreciable change in a perfectly pure glass vessel, whether the 
latter contains common air, or air previously heated to redness : 
but, at the same time, it absorbs oxygen, and emits carbonic aeid, 
and passes into putrefaction, if the necessary quantity of water 
be present, the process not being prevented or retarded by the ig- 
nition of the air. 

It cannot be supposed, that dung-flies, living upon animal ex- 
crements, are the cause of this putrefaction ; neither can a similar 
conclusion be drawn in the case of mites and maggots found so 
abundantly in old cheese. 

When we consider, that the intermediate products formed in 
the passage of animal and vegetable matters into inorganic com- 
pounds possess the power of supporting the life of certain ani- 
mals and vegetables low in the scale of creation, then the only 
mystery is, in what manner the germs of the fungi, or the eggs 
of the infusoria, reach the place fitted for their development ; for 
this being known, there is no difficulty since the discoveries of 
Ehrenberg, in conceiving this extraordinary increase. Now, as 
it is observed that the infusoria increase in size only to a certain 
point, it must hence be concluded that their nourishment, even if 
only from the point at which they are to grow, passes out of their 
bodies in the form of excrements, precisely as in the higher order 
of animals. As in the case with all other excrements, these 
must possess, in an eminent degree, the property of passing into 
decay or putrefaction ; and this condition must at all events be 
induced by contact with the original putrefying body. Hence 
the increase in numbers of the infusoria must induce and acce- 
lerate the process of putrefaction in the putrefying body itself. 
The ultimate products of decay and putrefaction are carbonic 



S52 FERMENTATION ASCRIBED TO THE 

acid, ammonia, and water. In order to comprehend the chemical 
process by which this conversion is effected, it is of much interest 
to become acquainted with the intermediate compounds formed 
by the elements. But in regard to the process itself, it is, che- 
mically speaking, quite indifferent whether the first, second, or 
third product, before they assume the final state, be in the form 
of fungi, or of living animals (infusoria). These plants and ani- 
mals are not the causes of the conversion, for they suffer after 
death the same changes which finally occasion their complete 
disappearance. 

The enormous layers of microscopic animals in the chalk (the 
siliceous infusoria) do not contain any organic matter. The lime 
of their shells, and the silica of their bony coverings, were ob- 
tained from the water in which they were developed. ]f this 
water had been deficient in lime, or in silica, these animals could 
not have been produced ; and if they had not found nourishment 
in the products of the putrefaction of former species (the remains 
of which are found in the muschelkalk), they would not have been 
developed ; and without the co-operation of both these causes, 
they could not have formed such extensive masses and layers as 
they actually do. 

But these animals are not the causes of the formation of the 
chalk, or of the layers of flint, and as little are they the cause of 
the decay and putrefaction of those substances, which yielded to 
them their organic constituents. Without these animals there 
might not have been chalk, but there would have been marble, or 
another limestone ; and the silica would have been deposited as 
siliceous schist, or as quartz, after the evaporation of the water. 
Hence it is only the form which is given to the layers by organic 
life ; but the substance of these strata (chalk) is chemically in no 
respect different from crystallized calcareous spar : in fact, the 
same explanation of their origin might be made as that adopted in 
the case of the older limestone formations. 

The conversion of the constituents of an elephant into aerial 
compounds is the same* process, and is effected by the same causes 
as those occasioning the destruction of the carcase of the micro- 
scopical animals, which themselves obtamed their elements from 



GROWTH OF FUNGI AND OF INFUSORIA. 333 

extinct species of other animals. The final products are identical 
in both cases. 

There have been very wonderful and incomprehensible ob- 
servations mac'e on the behavior and functions of certain mi- 
croscopic animals. From these observations, there seem to follow 
conclusions regarding the nutrition and growth of these creatures, 
quite at variance with all that we know of the process of nutrition 
of the higher classes of animals. 

In a treatise on the composition of the salt-springs in Hesse- 
Cassel, Pfannkuch mentions a singular phenomenon, that the 
slimy mass which deposits in the tub set to receive the brine per- 
colating through the wells of the graduating-house, contains a gas 
which is found to be pure oxygen gas. The fresh brine obtained 
directly from the draw-well is quite clear, and contains 5 per 
cent, of salt with gypsum and sulphuretted hydrogen in such con- 
siderable quantity that it might be used as a sulphureous water. 
During the summer months, a slimy transparent mass forms in 
this brine, covering the bottom of the vessel containing it to the 
depth of one to two inches. This matter is everywhere filled 
with bubbles of gas, of a considerable size, often two or three 
inches broad ; these rise to the surface, when the membrane in- 
closing them is torn with a stick. The quantity of these gas- 
bubbles is so great, that it would be easy to fill hundreds of 
bottles with them in a short time. They are so rich in oxygen 
gas, that a glowing match of wood introduced into the collected 
gas, bursts into flame, and continues to burn with brilliancy. On 
being analysed, this gas is found to consist of 51 per cent, of 
oxygen, and 49 per cent, of nitrogen ; but there can be little 
doubt that the gas originally consisted of pure oxygen, which be- 
came mixed with the nitrogen of air by virtue of diffusion, just as 
it does when confined in an animal membrane. In fact, it is 
found, that when the water in the tubs is very low, the bubbles 
existing in the deposit appear to be pure air, owing to the celerity 
with which the diffusion has taken place (Wohler). 

Wohler has subjected to microscopical examination the slimy 
membranous deposit, and has shown that it consists almost en- 
tirely of living and moving infusoria, principally species of Na- 
vicula and Gallionella, such as occur in the paper-like formations 



334 FERMENTATION ASCRIBED TO THE 



of Freiberg, and in tlie siliceous fossil strata of Franzensbad. 
The whole deposit possesses a slight greenish color, and is in- 
tersected with very fine colorless fibres of confervse. Aftei 
washing and drying the deposit, a residue like paper is obtained ; 
and this, on being heated, gives distinct indications of ammonia, 
showing that it contains nitrogen. It yields also a mass resem- 
bling paper, which, on incineration, being treated with muriatic 
acid, leaves behind siliceous skeletons, which preserve the shape 
of the animal so completely, that it appears as if the original de- 
posit itself were submitted to examination (Wohler). 

These observations are of remarkable interest, for, as Wohler 
asks — Whence comes the oxygen gas — from the confervse or from 
the infusoria ? The quantity of oxygen being so large, and the 
infusoria being in great preponderance, would lead to the con- 
clusion that the former must be derived from these ; and yet this 
is opposed to all analogy. The water comes out of a depth of 
500 feet ; and its sulphuretted hydrogen shows that it comes out 
of a layer of rocks containing putrefying animal matter, which, 
acting upon the sulphates, produces sulphuretted hydrogen ; and 
in this water is formed, with the aid of solar light, a source of 
oxygen gas, to all appearances more abundant than we see in the 
case of green plants. Sir B. Thompson (better known as Count 
Rumford) published some experiments 56 years since, which are 
of such a remarkable nature, that we give them in the author's 
own words. Thompson found that silk, cotton, sheep's wool, 
eider-down, and other organic substances, evolve oxygen gas, 
when they are freed from air by washing, and then exposed to 
sun-light in a glass globe perfectly filled with water. After two 
or three days, the water assumed a greenish hue, and from that 
moment the evolution of gas commenced. 

" One hundred and twenty grains of cotton, in a bell jar, 
along with 296 cubic inches of spring water, gave out, during 
the first four days, 2^ C. I. of gas, containing hardly any oxy- 
gen. It was not till the sixth day, when the sun was very pow- 
erful, that the water suddenly became green, and gave out dur- 
ing the next six days, 441 C. I. of oxygen nearly pure. On 
examining the water under the microscope, it was found to con- 
fain a multitude of very minute, nearly spherical animalcules. 



GROWTH OF FUNGI AND OF INFUSORIA. 33« 



Wherever the water was green, these animalcules were found, 
insomuch that the green color seemed to be caused by them." 
After describing his numerous experiments. Count Rumford 
adds — 

" The phenomena now described may, perhaps, admit of ex- 
planation, if we assume that the air produced in the water in the 
different experiments was derived from the green matter ; and 
that the leaves, silk, cotton, &;c., only facilitate its disengagement 
by furnishing a surface adapted to the collection and escape of 
the gas-bubbles. 

" These phenomena may also be explained by an assumption 
favorable to the hypothesis of Priestley, namely, that the green 
matter consists of plants, which, adhering to the surface of the 
bodies placed in the water, there vegetate, and in consequence 
give rise to the gas. 

" I would willingly adopt this opinion, were it not that a most 
careful and attentive examination of the green water by means 
of an excellent microscope, at the period when the oxygen was 
most abundantly disengaged, has convinced me, that at this pe- 
riod nothing to which the name of vegetable can be given is pre- 
sent. The coloring matter of the water is of an animal nature, 
and is nothing else than the accumulation of an infinite number 
of little moving animals." — Philosophical Transactions of the 
Royal Society, Vol. Ixxvii., 1787. 

In a very interesting memoir, by Messrs. August and Morren 
{Transactions of the Academy of Brussels, 1841), it is shown 
that water with organic substances evolves " a gas" which con- 
tains 61 per cent, of oxygen ; and they conclude their trea- 
tise in the following words : — " It follows from the preceding re- 
marks, that the phenomenon of the evolution of oxygen gas is 
due to the Chlamido7nonas pulvisculus (Khrenherg), and to several 
other green animals still lower in the scale." 

The author took the opportunity of convincing himself of the 
accuracy of this long-observed fact, by means of some water out 
of a water-trough in his garden, the water being colored strongly 
green by different kinds of infusoria. This water was freed by 
means of a sieve from all particles of vegetable matter, and be- 
ing placed in a jar, inverted in a porcelain vessel containing the 



336 FERMENTATION ASCRIBED TO THE 

same water, was exposed for several weeks to the action pf solar 
light. During this time, a continued accumulation of gas took 
place in the upper part of this jar ; after fourteen days ^ of the 
water in the jar had been pressed out of it, and the gas, which 
had taken its place, ignited a glowing match of wood, and in 
all respects behaved like pure oxygen gas. It must be here ex- 
pressly stated, that the water, before being exposed to the action 
of solar light, was examined by one of Ploessl's best micro- 
scopes, without the detection of confervse or of any kind of ve- 
getable matter.* 

Without venturing upon any opinion on the mode of nutrition 
of these animals, it is quite certain that water containing living 
infusoria becomes a source of oxygen gas when exposed to the 
action of light. It is also certain, that as soon as these animals 
can be detected in the water, the latter ceases to act injuriously 
to plants or animals ; for it is impossible to assume that pure 
oxygen gas can be evolved from water containing any decaying 
or putrefying matters, for these possess the property of combin- 
ing with oxygen. Now it is obvious, if we add to such water 
any animal or vegetable matter in a state of decay, that this, 
being in contact with oxygen, will resolve itself into the ultimate 
products of oxidation in a much shorter time than if infusoria 
were not present. 

Thus we recognise in these animals, or perhaps only in certain 
classes of them, by means of the oxygen which in some way, as 
yet incomprehensible, accompanies their appearance, a most wise 
and wonderful pi'ovision for removing from water the substances 
hurtful to the higher classes of animals ; and for substituting, in 
their stead, the food of plants (carbonic acid), and the oxygen 
gas essential to the respiration of animals. They cannot be 
viewed as the causes of putrefaction, or of the generation of pro- 
ducts injurious to animal and vegetable life ; but they make their 
appearance in order to accelerate the conversion of putrefying 
organic matter into its ultimate products, 

* One hundred cubic inches of water saturated with air contained, in 
the form of air, according to the experiments of Humboldt and Gay-Lus- 
sac, not above Tfi cubic inches of oxygen gas. 



GROW TH OF FUNGI AND OF INFUSORIA. 3r^l 



Many fungi grow without light, and in their growth and life 
are characterized by all the phenomena which characterize ani- 
mal life ; they destroy air by absorbing oxygen and evolving 
carbonic acid, and, in a chemical point of view, behave like ani- 
mals without motion. (See Appendix to Part II.) 

In opposition to this class of beings, which can scarcely be 
designated as plants, we have living creatures endowed with 
motion, and with the organs which characterize animals, and 
yet which behave in the light like green plants ; for while 
they increase in size and number, they furnish sources of oxy- 
gen when its access, in the form of air, is excluded or prevented. 

16 



WS DECAY OF WOODY FIBRE. 



CHAPTER XL 

Decay of Woody Fibre. 

'rHE conversion of woody fibre into the substances termed hu- 
mus and mould is, on account of its influence on vegetation, one 
of the most remarkable processes of decomposition in nature. 

Decay is not less nnportant in another point of view ; for, 
by means of its influence on dead vegetable matter, the oxy- 
gen retained by plants d ring life is again restored to the atmo- 
sphere. 

The decomposition of woody fibre is effected in three forms, 
the results of which are different, so that it is necessary to con- 
sider each separately. 

The first takes place when it is in the moist condition, and 
subject to free uninterrupted access of air ; the second occurs 
when the air is excluded ; and the third when the wood is covered 
with water, and in contact with putrefying organic matter. 

It is known that woody fibre may be kept under water, or in 
dry air, for thousands of years, without sufl'ering any appreci- 
able change ; but that when brought into contact with air, in the 
moist condition, it converts the oxygen surrounding it mto the 
same volume of carbonic acid, and is itself gradually changed 
into a yellowish-brown, or black matter, of a loose texture. Ac- 
cording to the expel iments of De Saussure, 240 parts of dry 
sawdust of oak-wood convert 10 cubic inches of oxygen into the 
same quantity of carbonic acid, which contains 3 parts, by weight, 
of carbon ; while the weight of the sawdust is diminished by 15 
parts. Hence, 12 parts, by weight, of water, are at the same 
time separated from the elements of the wood. 

Carbonic acid, water, and mould or humus, are therefore the 
products of the decomposition of wood. We have assumed that 
the water is formed by the combination of the hydrogen of the 



DECAY OF WOODY FIBRE. 333 

wood with the oxygen of the atmosphere, and that during the 
process of oxidation carbon and oxygen escape from the wood 
of carbonic acid. 

It has already been mentioned, that pure woody fibre con- 
tains carbon and the elements of water. Humus, however, is 
not produced by the decay of pure woody fibre, but by that of 
wood which contains foreign soluble and insoluble organic 
substances, besides its essential constituents. 

The relative proportions of the component elements are, on this 
account, different in oak wood and in beech, and the composition 
of both of these again differs from woody fibre, which is the same 
in all vegetables. The difference, however, is so trivial, that it 
may be altogether neglected in the consideration of the questions 
which will now be brought under discussion ; besides, the quan- 
tity of the foreign substances is not constant, but varies according 
to the season of the year. 

According to the careful analysis of Gay-Lussac and Thenai'd, 
100 parts of oak-wood, dried at 212'' (100° C), fi-om which all 
soluble substances had been extracted by means of water and 
alcohol, contained 52-53 parts of carbon, and 47-47 parts of hy- 
drogen and oxygen, in the same proportion as they are contained 
in water. 

Now it has been mentioned that moist wood acts in oxygen gas 
exactly as if its carbon combined directly with oxygen, and that 
the products of this action are carbonic acid and humus. 

If the action of the oxygen were confined to the carbon of the 
wood, and if nothing but carbon were removed from it, the re- 
maining elements would necessarily be found in the humus, un- 
changed, except in the particular of being combined with less 
carbon. The final result of the action would therefore be a com- 
plete disappearance of the carbon, whilst nothing but the ele- 
ments of water would remain. 

But when decaying wood is subjected to examination in dif- 
ferent stages of decay, the remarkable result is obtained, that 
the proportion of carbon in the different products augments. 
Consequently, if we did not take into consideration the evolution 
of carbonic acid under the influence of the air, the conversion 



340 DECAY OF WOODY FIBRE. 



of wood into humus might be viewed as a removal of the elements 
of water from the carbon. 

The analysis of mouldered oak-wood, taken from the interior 
of the trunk of an oak, and possessing a chocolate-bi'own color 
and the structure of wood, showed that 100 parts of it contained 
53-36 parts of carbon and 46-44 parts of hydrogen and oxygen 
in the same relative proportions as in water. From an examina- 
tion of mouldered wood of a light-brown color, easily reducible 
to a fine powder, and taken from another oak, it appeared that it 
contained 56-211 carbon and 43-789 water. 

These indisputable facts point out the similarity of the decay 
of wood, with all other instances of the slow combustion or oxi- 
dation of bodies containing a large quantity of hydrogen. Viewed 
as a kind of combustion, it would indeed be a very extraordinary 
process, if the carbon combined directly with the oxygen ; for 
it would be a combustion in which the carbon of the burning 
body augmented constantly, instead of diminishing. Hence it is 
evident that it is the hyjlrggen which is oxidi^d at the expense 
of the oxygen of the air ; while the carbonic acid is formed from 
the elements of the wood. Carbon never combines at common 
temperatures with oxygen, so as to form carbonic acid. 

In whatever stage of decay wood may be, its elements must 
always be capable of being reoresented. by their equivalent 
numbers. 

The following formulae illustrate this fact with great precision : 



C34 H,3 0,3- „ „ (Dr. WiiDj 

It is evident from these numbers, that for every two equiva- 
lents of hydrogen oxidized, two atoms of oxygen and one of car- 
bon are set free. 

Under ordinary circumstances, woody fibre requires a very 
long time for its decay ; but this process is of course much 

• The calculation from this formula gives 52-5 cai-bon, and 47"5 water 
t The calculation gives 54 carbon, and 46 water. 
X The calculation gives 56 carbon, and 44 water. 



DECAY OF WOODY FIBRE. 34' 

accelerated by an elevated temperature and free unrestrainea 
access of air. The decay, on the contrary, is much retarded by 
the absence of moisture, and by the wood being surrounded with 
an atmosphere of carbonic acid, which prevents the access of air 
to rhe decaying matters. 

Sulphurous acid, and all antiseptic substances, arrest the 
decay of woody fibre. It is well known that corrosive subli- 
mate is employed for the purpose of protecting the timber of 
ships from decay ; it is a substance which completely deprives 
vegetable or animal matters, the most prone to decomposition, of 
their property of entering into fermentation, putrefaction, or 
decay. 

But the decay of woody fibre is very much accelerated by 
contact with alkalies or alkaline earths ; for these enable sub- / 
stances to absorb oxygen, although they do not possess this/ 
power themselves : alcohol, gallic acid, tannin, the vegetable/ 
coloring matters, and several other substances, are thus affecteq 
by them. Acids produce quite an opposite effect ; they greatly 
retard decay. 

Heavy soils, consisting of loam, retain longest the most im- 
portant condition for the decay of the vegetable matter contained 
in them, viz. water ; but their impermeable nature prevents 
contact with the air. 

In moist sandy soils, particularly such as are composed of a 
mixture of sand and carbonate of lime, decay proceeds very 
quickly, it being aided by the presence of the slightly alkaline 
lime. 

Now let us consider the decay of woody fibre during a very 
long period of time, and suppose that its cause is the gradual 
removal of the hydrogen in the form of water, and the separation 
of its ox3'gen in that of carbonic acid. It is evident that if we 
snbtract from the formula Cgg Hgg Oj, the 22 equivalents of 
oxygen, with 11 equivalents of carbon, and 22 equivalents of 
hydrogen, which are supposed to be oxidized by the oxygen of 
the air, and separated in the form of water ; then from 1 atom of 
oak-wood, 25 atoms of pure carbon will remain as the final pro- 
duct of the decay. In other words, 100 parts of oak, containing 
52*5 parts of carbon, will leave as a residue 36-5 parts of car 



342 DECAY OF WOODY FIBRE. 

bon, which must remain unchanged, since carbon does not com- 
bine with oxygen at common tenrperatui'es. 

But this final result is never attained in the decay of wood 
under common circumstances ; and for this reason, that with the 
increase of the proportion of carbon in the residual humus, as in 
all decompositions of this kind, its attraction for the hydrogen, 
which still remains in combination, also increases, until at 
length the affinity of oxygen for the hydrogen is equalled by that 
of the carbon for the same element. 

In proportion as the decay of woody fibre advances, its pro- 
perty of burning with flame, or, in other words, of developing 
carburetted hydrogen on the application of heat, diminishes. 
Decayed wood burns without flame ; whence no other conclu- 
sion can be drawn, than that the hydrogen, which analysis 
shows to be present, is not contained in it in the same form as 
in wood. 

Decayed oak contains more carbon than fresh wood, but its 
hydrogen and oxygen are in the same proportion to each other, 
that is, in the proportion to form water. 

We should naturally expect that the flame given out by de- 
cayed wood should be more brilliant in proportion to the increase 
of its carbon, but we find, on the contrary, that it burns like 
tinder, exactly as it no hydrogen were present. For the pur- 
poses of fuel, decayed or diseased wood is of little value, for it 
does not possess the property of burning with flame — a property 
upon which the advantages of common wood depend. The 
hydrogen of decayed wood must, consequently, be supposed to 
be in the state of water ; for had it any other form, the charac- 
ters we have desca-ibed would not be possessed by the decayed 
wood. 

If we suppose decay to proceed in a liquid containing much 
carbon and hydrogen, then a compound with still more carbon 
must be formed, in a manner similar to the production of the 
crystalline colorless naphthalin from a gaseous compound of car- 
bon and hydrogen. And if the compound thus formed were 
itself to undergo further decay, the final result must be the sepa- 
ration of carbon in a crystalline form. 

Science can point to no process capable of accounting for tha 



DECAY OF WOODY FIBRE. 343 

origin and formation of diamonds, except the process of decay. 
Diamonds cannot be produced by the action of fire ; for a high 
temperature, and the presence of oxygen gas, would call into 
play their combustibility. But there is the greatest reason to 
believe that they are formed in the humid way — that is, in a 
liquid, and the process of decay is the only cause to which their 
formation can with probability be ascribed. 

Amber, fossil resin, and the acids in mellite, are the products 
of vegetable matter which has suffered eremacausis. They are 
found in wood (or brown) coal, and have evidently proceeded 
from the decomposition of substances which were contained in 
quite a different form in the living plants. They are all distin- 
guished by their proportionally small quantity of hydrogen. The 
acid from mellite (mellitic acid) contains precisely the same pro- 
portions of carbon and oxygen as that from amber (succinic 
acid) ; they differ only in the proportion of their hydrogen. 
Succinic acid may be obtained by oxidation from wax and all 
other solid fats. 



344 VEGETABLE MOULD. 



CHAPTER XII. 

Vegetable Mjuld. 

The term vegetable mould, in its general signification, is 
applied to a mixture of disintegrated minerals, with the remains 
of animal and vegetable substances. It may be considered as 
earth in which humus is contained in a state of decomposition. 
Its action upon the air has been fully investigated by Ingenhouss 
and Ue Saussure. 

When moist vegetable mould is placed in a vessel full of air, it 
extracts the oxygen therefrom with greater rapidity than decayed 
wood, and replaces it by an equal volume of carbonic acid. 
When this carbonic acid is removed, and fresh air admitted, the 
same action is repeated. 

Cold water dissolves only -f-ooinrth of its own weight of vege- 
table mould ; the solution is clear and colorless, and the residue 
left on its evaporation consists of common salt with traces of sul- 
phate of potash and lime and a minute quantity of organic mat- 
ter, for it is slightly blackened when heated to redness. Boiling 
water extracts several substances from vegetable mould, and 
acquires a yellow or yellowish brown color, which is dissipated 
by absorption of oxygen from the air, a black flocculent deposit 
being formed. When the colored solution is evaporated, a 
residue is left which becomes black on being heated to redness, 
and afterwards yields carbonate of potash when treated with 
water. 

A solution of caustic potash becomes black when placed in 
contact with vegetable mould, and the addition of acetic acid to 
the colored solution causes no precipitate or turbidity. But 
dilute sulphuric acid throws down a light flocculent precipitate 
of a brown or black color, from which the acid can be removed 
with difficulty by means of water. When this precipitate, after 



VEGETABLE MOULD. ~ 345 

having been washed with water, is brought whilst still moist 
under a receiver filled with oxygen, the gas is absorbed with 
great rapidity ; and the same thing takes place when the pre- 
cipitate is dried in the air. In the perfectly dry state it has en- 
tirely lost its solubility in water, and even alkalies dissolve only 
traces of it. 

It is evident, therefore, that boiling water extracts a matter 
from vegetable mould, which owes its solubility to the presence 
of the alkaline salts contained in the remains of plants. This 
snbstance is a product of the incomplete decay of woody fibre, 
and contains a certain quantity of ammonia chemically combined. 
Its composition is intermediate between woody fibre and humus, 
into which it is converted, by being exposed in a moist condition 
.o the action of the air. 



// 



34« MOULDERING OF BODIES. 



CHAPTER XIII. 

On the Mouldering of Bodies. — Paper, Brown Coal, and Mineral Coal. 

The decomposition of wood, woody fibre, and all vegetable bodies 
when subjected to the action of water, and excluded from the air, 
is termed mouldering. 

Wood (or brown coal) and mineral coal, are the remains of 
r J vegetables of a former world ; their appearance and characters 
I ^ show that they are products of the processes of decomposition 
termed decay and putrefaction. We can easily ascertain by ana- 
lysis the manner in which their constituents have been changed, 
if we suppose the greater part of their bulk to have been formed 
from woody fibre. 

But it is necessary, before we can obtain a distinct idea of the 
manner in which coal is formed, to consider a peculiar change 
which woody fibre suffers by means of moisture, when partially 
or entirely excluded from the air. 

It is known that when pure woody fibre, as linen, for example, 
is placed in contact with water, considerable heat is evolved, and 
the substance is converted into a soft friable mass, which has in 
a great degree lost its coherence. This substance was employed 
in the fabrication of paper before the use of chlorine, as an agent 
for bleaching. The rags employed for this purpose were placed 
in heaps ; and it was observed, that on their becoming warm a 
gas was disengaged, and their weight diminished from 18 to 25 
oer cent. 

When sawdust moistened with water is placed in a closed 
ressel, carbonic acid gas is evolved in the same manner as when 
air is admitted. A true putrefaction takes place, the wood as- 
sumes a white color, loses its peculiar texture, and is converted 
into a rotten friable matter. 

The white decayed wood found in the interior of trunks of 



DECOMPOSITION OF WOOD, COAL, ETC. 347 



dead trees which have been in contact with water, is produced 
in the way just mentioned. 

An analysis of wood of this kind, obtained from the interior 
of the trunk of an oak, yielded, after having been dried at 212*^, 



Carbon 


- 


- 47-11 


. 


. 


- 48-14 


Hydrogen 


- 


- 6-31 


- 


- 


- 6-06 


Oxygen 


- 


- 45-31 


- 


. 


- 44-43 


Ashes 


- 


- 127 


- 


- 


- 1-37 



10-000 100-00 

Now, on comparing the proportions obtained from these num- 
bers with the composition of oak wood, according to the analysis 
of Gay-Lussac and Thenard, it is immediately perceived that a 
certain quantity of carbon has been separated from the constitu- 
ents of wood, whilst the hydrogen is, on the contrary, increased. 
The numbers obtained by the analysis correspond very nearly to 
the formula C33 Hg 7 02 4-* 

The elements of water have, therefore, along with a certain 
amount of oxygen from the air, become united with the wood, 
whilst carbonic acid is separated from it. 

If the elements of 5 atoms of water and 3 atoms of oxygen be 
added to the composition of the woody fibre of the oak, and three 
atoms of carbonic acid deducted, the exact formula for white 
mouldered wood is obtained. 

Wood - - - - C,„ H„„ 0„„ 

3 6 2 2 gS 

±0 this add 5 atoms of water - - H g 

3 atoms of oxygen - - - - g 



^36 "27 O30 



Subtract from this 3 atoms carbonic acid C 



C33H,, o,. 



The process of mouldering is, therefore, one of putrification 
and decay, proceeding simultaneously, in which the ox5^gen of 

♦ The calculation from this formula gives in 100 parts 47 9 carbon, 6-1 
hydrogen, and 46 oxygen. 



348 MOULDERING OF BODIES. 

the air and the component parts of water take part. But the 
composition of mouldered wood must change according as the 
access of oxygen is more or less prevented. White mouldered 
beech-wood yielded on analysis 47'67 carbon, 5-67 hydrogen, 
and 46-68 oxygen; this corresponds to the formula Cjj Hjs 

The decomposition of wood assumes, therefore, two different 
forms, according as the access of the air is free or restrained. 
In both cases carbonic acid is generated ; and in the latter case, 
a certain quantity of water enters into chemical combination. 

It is highly probable that in this putrefactive process, as well 
as in all others, the oxygen of the water assists in the formation 
of the carbonic acid. 

Wood-coal (brown coal of Werner) must have been produced 
by a process of decomposition similar to that of mouldering 
But it is not easy to obtain wood-coal suited for analysis, for it 
is generally impregnated with resinous or earthy substances, by 
which the composition of those parts which have been formed 
from woody fibre is essentially changed. 

The wood-coal, which forms extensive layers in the Wetterau 
(a district in Hesse-Darmstadt), is distinguished from that found 
in other places, by possessing the structure of wood unchanged, 
and by not containing bituminous matter. This coal was sub- 
jected to analysis, a piece being selected upon which the annual 
circle could be counted. It was obtained from the vicinity of 
Laubach ; 100 parts contained 

Carbon 57-28 

Hydrogen ------ 6'03 

Oxygen .-.-.- 36']0 

Ashes 0-59 



100-00 



The large amount of carbon, and small quantity of oxygen, 
constitute the most obvious difference between this analysis and 
that of wood. It is evident that the wood which has undergone 
the change into coal must have parted with a certain portion of 



FORMATION OF WOOD COAL. 349 

its oxygen. The proportion of these numbers is expressed by 
the formula C33 H^ 1 Oig.* 

When those numbers are compared with those obtained by 
tlie analysis of oak, it would appear that the brown coal was pro- 
duced from woody fibre by the separation of one equivalent 
of hydrogen, and the elements of three equivalents of carbonic 
acid. 

1 atom wood ...... C36H22O22 

Minus 1 atom hydrogen and 3 atoms car- } ri u n 
bonicacid . . . J C 9H lO 6 



Wood Coal . CasHsiOis 

All varieties of wood-coal, from whatever strata they may be 
taken, contain more hydrogen than wood does, and less oxygen 
tha,n is necessary to form water with this hydrogen ; conse- 
quently they must all be produced by the same process of decom- 
position. The excess of hydrogen is either hydrogen of the wood 
remaining in it unchanged, or it is derived from some exterior 
source. The analysis of wood-coal from Ringkuhl, near Cassel, 
where it is seldom found in pieces with the structure of wood, 
gave, when dried at 212°, 



Carbon . 


. 62-60 . 


. 63-83 


Hydrogen . 


502 


4-80 


Oxygen . 


. 26-52 . 


. 25 51 


Ashes 


5-86 


5-86 



100-00 10000 

The proportions derived from these numbers correspond very 
closely to the formula C32 Hi 5 O9, or they represent the con- 
stituents of wood, from which the elements of carbonic acid, 
water, and 2 equivalents hydrogen, have been separated. 

C 3 6 Ha 2 02 2 ^Wood. 
Subtract C 4 H 7 Oi 3=4 atoms carbonic acid + 5 atoms of water 
+2 atoms of hydrogen. 



Cj2 His O 9=Wood Coal from Ringkuhl. 
• The calculation gives 57-5 carbon, and 5-98 hydrogen. 



350 CONVERSION OF WOOD 

The formation of both these specimens of wood-coal appears 
from these formulae to have taken place under eircumstancea 
wiiicli did not entirely exclude the action of the air, and conse- 
quent oxidation and removal of a certain quantity of hydrogen. 
Now the Laubacher coal is covered with a layer of basalt, and 
the coal of Ringkuhl was taken from the lowest seam of layers, 
which possess a thickness of from 90 to 120 feet ; so that both 
may be considered as well protected from the air. 

During the formation of brown coal, therefore, the elements of 
carbonic acid have been separated from the wood either alone, 
or at the same time with a certain quantity of water. It is quite 
possible that the difference in the process of decomposition may 
depend upon the high temperature and pressure under which the 
decomposition took place. At least, a piece of wood assumed the 
character and appearance of Laubacher coal, after being kept 
for several weeks in the boiler of a steam-engine, and had then a 
very similar composition. The change in this case was effected 
in water, at a temperature of from 334° to 352° F. (150° to 160° 
C), and under a corresponding pressure. The ashes of the wood 
amounted to 0-51 per cent.; a little less, therefore, than these of 
the Laubacher coal ; but this must be ascribed to the peculiar 
circumstances under which it was formed. The ashes of plants 
examined by Berthier amounted always to much more than this. 

The peculiar process by which the decomposition of these 
extinct vegetables has been effected, namely, a disengagement 
of carbonic acid ' from their substance, appears still to go on at 
great depths in all the layers of wood-coal. At all events, it is 
remarkable that springs impregnated with carbonic acid occur in 
many places, in the country between the Meissner, in the electorate 
of Hesse, and the Eifel, which are known to possess large layers 
of wood-coal. These springs of mineral water are produced on 
the spot at which they are found ; the springs of conmion water 
meeting with carbonic acid during their ascent, and becoming 
impregnated with it. 

In the vicinity of the layers of wood-coal at Salzhausen 
(Hesse-Darmstadt), an excellent acidulous spring of this kind 
existed a few years ago, and supplied all the inhabitants of that 
district ; but it was considered advantageous to surround the 



INTO BROWN OR WOOD- COAL. 3,^)1 

sides of the spring with sandstone, and the consequence was, tliat 
all the outlets to the carbonic acid were closed, for this gas 
generally gains access to the water from the sides of the sprinor. 
From that time to the pi-esent this valuable mineral water has 
disappeared, and in its place is found a spring of common 
water. 

Springs of water impregnated with carbonic acid occur at 
Schwalheim, at a very short distance from the layers of wood-coal 
at Dorheim. M. Wilhelmi observed some time since, that they 
are formed of common spring water, which ascends from below, 
and of carbonic acid, which issues from the sides of the spring. 
The same fact has been shown to be the case in the famed 
Fachinger spring, by M. Schapper. 

The carbonic acid gas from the springs in the Eifel is, accord- 
ing to BischofT. seldom mixed with nitrogen or oxygen, and is 
probably produced in a manner similar to that just described. 
At any rate, the air does not appear to take any part in the 
formation of these acidulous springs. Their carbonic acid has 
evidently not been formed either by a combustion at high or low 
temperatures ; for if it were so the gas resulting from the com- 
bustion would necessarily be mixed with f of nitrogen, but it 
does not contain a trace of this element. The bubbles of gas 
which escape from these springs are absorbed by caustic potash, 
with the exception of a residuum too small to be appreciated. 

The wood-coal of Dorheim and Salzhausen must have been 
formed in the same way as that of the neighboring village 
of Laubach ; and since the latter contains the exact elements of 
woody fibre, minus a certain quantity of carbonic acid, its com- 
position indicates very plainly the manner in which it has been 
produced. 

The coal of the upper bed is subjected to ar incessant decay 
by the action of the air, by means of which its hydrogen 
is removed in the same manner as in the decay of wood. This 
is recognised by the way in which it burns, and by the formation 
of carbonic acid in the mines. 

The gases which are formed in mines of wood- coal, and cause 
danger in their working, are not combustible or inflammable as 
in mines of mineral coal ; but they consist generally of carbonic 



?J,2 CONVERSION OF WOOD 

acid gas, and are very seldom intermixed with combustiblo 
gases. 

Wood-coal from the middle bed of the strata at Ringkuhl gave 
on analysis 65-40 — 64'01 carbon, and 4*75 — 4-70* hydrogen ; 
the proportion of carbon here is the same as in specimens 
procured from greater depths, but that of the hydrogen is much 
less. 

Wood and mineral coal are always accompanied by iron 
pyrites (sulphuret of iron) or zinc blende (sulphuret of zinc) ; 
which minerals are still formed from salts of sulphuric acid, with 
iron or zinc, during the putrefaction of all vegetable matter. It 
is possible that the oxygen of the sulphates in the layers of wood- 
coal is the means by which the removal of the hydrogen is 
effected, since wood-coal contains less of this element than wood. 

According to the analysis of Richardson and Regnault, the 
composition of the combustible materials in splint coal from 
Newcastle, and cannel coal from Lancashire, is expressed by the 
formula C.^^ H,, O. When this is compared with the composi- 
tion of woody-fibre, it appears that these coals are formed from 
its elements, by the removal of a certain quantity of carburetted 
hydrogen and carbonic acid, in the form of combustible oils. 
The composition of both of these coals is obtained by the subtrac- 
tion of 3 atoms of carburetted hydrogen, three atoms of water, 
and 9 atoms of carbonic acid from the formula of wood. 

'36 22^22 =wood 
3 atoms of carburetted hydrogen C s H 



3 atoms of water . . . H 3 
9 atoms of carbonic acid . C 9 



Mineral coal 



C:2H 9O21 
Ca 4 Hi 3 O 



Carburetted hydrogen generally accompanies all mineral coal ; 
other varieties of coal contain volatile oils which may be sepa- 
rated by distillation with water. (Reichenbach.) This origin of 
naphtha is owing to a similar process of decomposition. Caking 
coal from Caresfield, near Newcastle, contains the elements of 
cannel coal, minus the constituents of defiant gas C4 H4. 

* The analysis of brown coal from Ringkuhl, as well as all those of th« 
same substance given in this work, have been executed in this laboratorj 
by M. Khunert, of Cassel. 



INTO MINERAL COAL. as3 

The inflammable gases which stream out of clefts in the strata 
of mineral coal, or in rocks of the coal formations, always con- 
tain carbonic acid, according to a recent examination by BischofT, 
and also carburetted hydrogen, nitrogen, and defiant gas ; the 
last of which had not been observed, until its existence in these 
gases was pointed out by Bischoff. The analysis of Jire-damp, 
after it had been treated with caustic potash, showed its consti- 
tuents to be — 



Gas from an 

.abandoned 

n.ine near 

Wallesvveiller. 

Vol. 


Gerhard's pas- 
sage near 
Luisenthal. 
yel. 


Gas from a 
mine near 
Liekwege. 
Vol.- 


Light carburetted hydrogen 9r3« 
Olefiantgas - - 6-32 


8308 
1-98 


89-10 
6-11 


Nitrogen gas - - 2-32 


14-94 


4-79 



10000 10000 10000 

The evolution of these gases proves that changes are constantly 
proceeding in the coal. 

It is obvious from this, that a continual removal of oxygen in 
the form of carbonic acid is effected from layers of wood-coal, 
in consequence of which the wood must approach gradually to 
the composition of mineral coal. Hydrogen, on the contrary, is 
disengaged from the constituents of mineral coal in the form of 
a compound of hydro-carbon ; a complete removal of all the 
hydrogen would convert coal into anthracite. 

The formula Cjg Hjg ^m which is given for wood, has been 
chosen as the empirical expression of the analysis, for the pur- 
pose of bringing all the transformations which woody fibre is 
capable of undergoing under one common point of view. 

Now, although the correctness of this formula must be doubted, 
until we know with certainty the irue constitution of woody fibre, 
this cannot have the smallest influence on the account given of 
the changes to which wood fibre must necessarily be subjected 
in order to be converted into wood or mineral coal. The theore- 
Ileal expression refers to the absolute quantity, the empirical 
merely to the relative proportion, in which the elements of a body 
are united. Whatever form the first may assume, the empirical 
expression must always remain unchanged. 



«4 POISONS, CONTAGIONS, MIASMS. 



chapti*:r XV. 

On Poisons, Contagions, and Miasms. 

A GREAT many chemical compounds, some derived from inorganic 
nature, and others formed in animals and plants, produce pecu- 
liar changes or diseases in the living animal organism. They 
disturb the vital functions of individual organs ; and when their 
action attains a certain degree of intensity, death is the conse- 
quence. 

The action of inorganic compounds, such as acids, alkalies, 
metallic oxides, and salts, can in most cases be easily explained. 
They either destroy the continuity of particular organs, or they 
enter into combination with their substance. The action of sul- 
phuric, muriatic, and oxalic acids, hydrate of potash, and all 
those substances which produce the direct destruction of the 
organs with which they come into contact, may be compared to 
a piece of iron, which can cause death by inflicting an injury 
on particular organs, either when heated to redness, or when in 
the form of a sharp knife. Such substances are not poisons 
in the limited sense of the word, for their injurious action depends 
merely upon their condition. 

The action of the proper inorganic poisons is owing, in most 
cases, to the formation of a chemical compound by the union of 
the poison with the constituents of the organ upon which it acts ; 
it is owing to an exercise of a chemical affinity more powerfu' 
than the vitality of the organ. 

It is well to consider the action of inorganic substances in 
general, in order to obtain a clear conception of the mode of 
action of those which are poisonous. We find that certain 
soluble compounds, when presented to different parts of the body, 
are absorbed by the blood, wlience they are again eliminated 



EFFECTS OF SALTS ON THE ORGANISM. 35S 

by the organs of secretion, either in a changed or in an un- 
changed state. 

Iodide of potassium, sulpho-cyanuret of potassium, ferro- 
cyanuret of potassium, chlorate of potash, silicate of potash, and 
all salts with alkaline bases, when administered internally to man 
and animals in dilute solutions, or applied externally, may be 
again detected in the blood, sweat, chyle, gall, and splenic veins ; 
but all of them are finally excreted from the body through the 
urinary passages. 

Each of these substances, in its transit, produces a peculiar 
disturbance in the organism — in other words, they exercise a 
medicinal action upon it, but they themselves suffer no decom- 
position. If any of these substances enter into combination with 
any part of the body, the union cannot be of a permanent kind ; 
for their re-appearance in the urine shows that any compounds 
thus formed must have been again decomposed by the vital 
processes. 

Neutral citrates, acetates, and tartrates of the alkalies suffer 
change in their passage through the organism. Their bases can 
indeed be detected in the urine, but the acids have entirely dis- 
appeared, and are replaced by carbonic acid, which has united 
with the bases. (Gilbert Blane and Wohler.) 

The conversion of these salts of organic acids into carbonates, 
indicates that a considerable quantity of oxygen must have 
united with their elements. In order to convert one equivalent 
of acetate of potash into the carbonate of the same base, 8 equi- 
valents of oxygen must combine with it, of which either 2 or 4 
equivalents (according as an acid or neutral salt is produced) 
remain in combination with the alkali ; whilst the remaining 
or 4 equivalents are disengaged as free carbonic acid. There is 
no evidence presented by the organism itself, to which these salts 
i)ave been administered, that any of its proper constituents have 
yielded so great a quantity of oxygen as is necessary for their 
conversion into carbonates. Their oxidation can, therefore, only 
be ascribed to the oxygen of the air. 

During the passage of these salts through the lungs, their 
acids take part in the peculiar process of eremacausis proceed. 
ing in that organ ; a certain quantity of the oxygen gas inspired 



356 POISONS, CONTAGIONS, MIASMS 

unites with their constituents, anil converts the<r hydrogen into 
water, and their carbon into carbonic acid. Part of this latter 
product (1 or 2 equivalents) remains in combination with the 
alkaline base, forming a salt which suffers no further change by 
the process of oxidation ; and it is this salt which is separated by 
the kidneys or liver. 

It is manifest that the presence of these organic salts in the 
blood must produce a change in the process of respiration. A 
part of the oxygen inspired, which usually combines with the 
constituents of the blood, must, when they are present, combine 
with their acids, and thus be prevented from performing its 
usual office. The immediate consequence of this must be the 
formation of arterial blood in less quantity, or, in other words, 
the process of respiration must be retarded. 

Neutral acetates, tartrates, and citrates placed in contact with 
the air, and at the same time with animal or vegetable bodies in 
a state of eremacausis, produce exactly the same effects as we 
have described them to produce in the lungs. They participate 
in the process of decay, and are converted into carbonates just as 
in the living body. If impure solutions of these salts in water 
are left exposed to the air for any length of time, their acids are 
gradually decomposed, and at length entirely disappear. 

Free mineral acids, or organic acids without volatility, and 
salts of mineral acids with alkaline bases, completely arrest 
decay when added to decaying matter in sufficient quantity ; 
and when their quantity is small, the process of decay is pro- 
tracted and retarded. They produce in living bodies the same 
phenomena as the neutral organic salts, but their action depends 
upon a different cause. 

The absorption by the blood of a quantity of an inorganic salt 
sufficient to arrest the process of eremacausis in the lungs, is 
prevented by a very remarkable property of all animal mem- 
branes, skin, cellular tissue, muscular fibre, &c. ; namelv, by 
their incapability of being permeated by concentrated sa'ine 
solutions. It is only when these solutions are diluted to a 
certain degree with water that they are absorbed by animal 
tissues. 

A dry bladder remains more or less dry in saturated solu- 



EFFECTS OF SALTS ON THE ORGANISM. 35" 

tions of common salt, nitre, ferro-cyanuret of potassium, sulpho- 
cyanui'et of potassium, sulphate of magnesia, chloride of potas- 
sium, and sulphate of soda. These solutions run off its surface 
in the same manner as water runs from a plate of glass be- 
smeared with tallow. 

Fresh flesh, over which salt has been strewed, is found, 
after 24 hours, swimming in brine, although not a drop of water 
has been added. The water has been yielded by the muscular 
fibre itself, and having dissolved the salt in immediate contact v 
with it, and thereby lost the power of penetrating animal sub- ' 
stances, it has on this account separated from the flesh. The ', 
water still retained by the flesh contains a proportionally small ^ 
quantity of salt, having that degree of dilution at which a saline 
fluid is capable of penetrating animal substances. 

This property of animal tissues is taken advantage of in 
domestic economy for the purpose of removing so much water 
from meat that a sufficient quantity is not left to enable it to \ 
enter into putrefaction. 

In respect of this physical property of animal tissues, alcohol 
resembles the inorganic salts. It is incapable of moistening, that 
is, of penetrating, animal tissues, and possesses such an affinity | 
for water as to extract it from moist substances. 

When a solution of a salt, in a certain degree of dilution, is in- 
troduced into the stomach, it is absorbed ; but a concentrated ■ 
saline solution, in place of being itself absorbed, extracts water 
from the organ, and a violent thirst ensues. Some interchange 
of water and salt takes place in the stomach ; the coats of this 
viscus yield water to the solution, a part of which, having pre- 
viously become sufficiently diluted, is, on the other hand, ab- 
sorbed. But the greater part of the concentrated solution of salt 
remains unabsorbed, and is not removed by the urinary pas- 
sages ; it consequently enters the intestines and intestinal canal, 
where it causes a dilution of Ihe solid substances deposited 
there, and thus acts as a purgnfive. 

Each of the salts just mentioned possesses this purgative 
action, which depends on a physical property shared by all of 
them ; but, besides this, they exercise a medicinal action, be- 



858 POISONS, CONTAGIONS, MIASMS. 



cause every part of the organism with which they come in con- 
tact absorbs a certain quantity of them. 

The composition of the salts has nothing to do with their pur- 
gative action ; it is quite a matter of indifference as far as the 
mere production of this action is concerned (not as to its inten- 
sity), whether the base be potash or soda, or in many cases lime 
and magnesia ; and whether the acid be phosphoric, sulphuric, 
nitric, or hydrochloric. 

If we diink, fasting, a glass of common spring water every 
ten minutes, a strong diuretic action becomes apparent, the 
quantity of salts in the water being much less than that in the 
blood. 

When the second glass is taken, a quantity of urine is eliiru- 
nated, the weight and volume of which corresponds nearly to 
that of the first glass ; and by drinking twenty successive 
glasses of water, nineteen evacuations of urine take place, the 
last of which is colorless, and scarcely diffei's in its amount of 
saline ingredients from the spring water itself. 

When the same experiment is made with a water contain- 
ing exactly the amount of salts as in blood (^ to 1 per cent, 
of common salt for example), a separation of urine is not 
effected, and it becomes almost impossible to drink more 
than three glasses of such water. A sensation of fulness 
in the stomach, of pressure and weight, seems to show that 
water containing an equal amount of saline ingredients as blood, 
requires a much longer time to be taken up by the blood- 
vessels. 

When the water taken contains a larger amount of salts 
than that existing in blood, a more or less active purgative 
action ensues. Hence, we see that three kinds of action take 
place, according to the quantities of salt existing in the water. 

Besides these salts, the action of which does not depend upon 
their power of entering into combination with the component 
parts of the organism, there is a large class of others which, 
when introduced into the living body, effect changes of a very 
different kind, and produce diseases or death, according to the 
nature of these changes, without effecting a visible lesion of any 
organs. 



INORGANIC POISONS 359 



These are the true inorganic poisons, the action of which de- 
pends upon their power of" forming permanent compounds with 
the substance of the membranes and muscular fibre. 

Salts of lead, iron, bismuth, copper, and mercury, belong to 
this class. 

When solutions of these salts are treated with a sufficient 
quantity of albumen, milk, muscular fibre, and animal mem- 
branes, they enter into combination with those substances, and 
lose their own solubility ; while the water in which they wore 
dissolved loses all the salt which it contained. 

The' salts of alkaline bases extract water from animal sub- 
stances ; whilst the salts of the heavy metallic oxides are, on the 
contrary, extracted from the water, for they enter into combina- 
tion with the animal matters. 

Now, when these substances are administered to an animal, 
they lose their solubility by entering into combination with 
the membranes, cellular tissue, and muscular fibre ; but in 
very few cases can they reach the blood. According to all 
the experiments yet made on the subject, it appears, that after 
the lapse of the same time as is required for the appearance 
of alkaline salts in the urine, the metallic salts above mentioned 
cannot be detected in that fluid. In fact, during their passage 
through the organism, they come into contact with many sub- 
stances by which they are retained. By degrees, however, the 
constituents of the tissues with which they have combined are 
altered by the change of matter ; their nitrogen appears in the 
urine, and along with it the mineral elements previously com- 
bined with the organic matter, such as mercury, copper, &;c. 
When such substances enter into combination with organized 
parts, the functions of those parts must be disturbed, and must 
take an abnormal direction, producing morbid phenomena. 

The action of corrosive sublimate and arsenious acid is very 
remarkable in this respect. Corrosive sublimate and other 
salts of mercury combine chiefly with albumen and albuminous 
tissues. 

Arsenious acid enters into a very firm combination with mem- 
branes and gelatinous tissues. A piece of fresh skin, or a blad- 
tior which, if covered with water, liquefy in a few weeks into a 



M 



350 . POISONS, CONTAGIONS, MIASMS. 

fetid, putrid mass, retain all their properties unchanged if ar 
senious acid be added to the water. The arsenious acid, combining 
with these tissues, gives to them the power of resisting decay 
and putrefaction. The putrefaction of flesh, or of blood, and 
the fermentation of sugar, are not checked or prevented by ar- 
senious acid. 

It is further known that the parts of a body which come in con- 
tact with these substances during poisoning, and which therefore 
enter into combination with them, do not afterwards putrefy ; so 
that there can be no doubt regarding the cause of their poisonous 
qualities. 

It is obvious that if arsenious acid and corrosive sublimate are 
not prevented by the vital principle from entering into combi- 
nation with the component parts of the body, and consequently 
from rendering them incapable of decay and putrefaction, they 
must deprive the organs of the principal property which apper- 
tains to their vital condition, viz. that of suffering and effecting 

} \ transformations ; or, in other words, organic life must be de- 
stroyed. If the poisoning is merely superficial, and the quantity 
of the poison so small that only individual parts of the body ca- 
pable of being regenerated have entered into combination with it, 
then eschars are produced — a phenomenon of a secondary kind 
— the compounds of the dead tissues with the poison being thrown 
off by the healthy parts. From these considerations it may readily 
be inferred that all internal signs of poisoning are variable and 
uncertain ; for cases may happen, in which no apparent indica- 
tion of change can be detected by simple observations of the parts, 
because, as has been already remarked, death may occur without 
the destruction of any organs. 

, When arsenious acid is administered in solution, it may enter 
1 1 into the blood. If a vein is exposed and surrounded with a solu- 
tion of this acid, every blood-globule will combine with it, that is, 
will become poisoned. 

The compounds of arsenic, which have not the property of en. 
tering into combination with the tissues of the organism, are 
without influence on life, even in large doses. Many insoluble 
basic salts of arsenious acid are known not to be poisonous. The 
substance called alkargen, discovered by Bunsen, has not tho 



INORGANIC POISONS. 361 

slightest injurious action upon the organism ; yet it contains a 
very large quantity of arsenic, and approaches very closely in 
composition to organic compounds. 

These considerations enable us to fix with tolerable certainty 
the limit at which the above substances cease to act as poisons. 
For since their combination with organic matters must be regu- 
lated by chemical laws, death will inevitably result, when 
the organ in contact with the poison finds sufficient of it to 
unite with atom for atom ; whilst if the poison is present 
in smaller quantity, a part of the organ will retain its vital 
functions. 

All substances administered as antidotes in cases of poisoning, 
act by destroying the power which arsenious acid and corrosive 
sublimate possess, of entering into combination with animal mat 
ters, and of thus acting as poisons. Unfortunately no other body 
surpasses them in that power, and the compounds which they 
form can only be broken up by affinities so energetic, that their 
action is as injurious as that of the above-named poisons them- 
selves. The duty of the physician consists, therefore, in his 
causing those parts of the poison which may be free and still un- 
combined, to enter into combination with some other body, so as 
to produce a compound incapable of being decomposed or digested 
in the same conditions. Hydrated peroxide of iron is an in- 
valuable substance for this purpose. 

When the action of arsenious acid or corrosive sublimate is 
confined to the surface of an organ, those parts only are destroyed 
which enter into combination with it ; an eschar is formed, and 
is gradually thrown off". 

Soluble salts of silver would be quite as deadly a poison as 
corrosive sublimate, did not a cause exist in the human body by 
which their action is prevented, unless their quantity is very 
great. This cause is the presence of common salt in all animal 
liquids. Nitrate of silver, it is well known, combines with ani- 
mal substances, in the same manner as corrosive sublimate, and 
the compounds formed by both are exactly similar in the character 
of being incapable of decay or putrefaction. 

When nitrate of silver in a state of solution is applied to skin 
or muscular fibre, it combines with them instantaneously j aiii* 
17 



962 POISONS, CONTAGIONS, MIASMS. 

mal substances dissolved in any liquid are precipitated by it, and 
rendered insoluble, or, as it is usually termed, they are coagu- 
lated. The compounds thus formed are colorless, and so stable, 
that they cannot be decomposed by other powerful chemical 
agents. They are blackened by exposure to light, like all othei 
compounds of silver, in consequence of a part of their oxide ol 
silver being reduced to the metallic state. Parts of the body 
united to salts of silver no longer belong to the living organism, 
for their vital functions have been arrested by combination with 
oxide of silver ; and if they are capable of being reproduced, 
the neighboring living structures throw them off in the form of an 
eschar. 

When nitrate of silver is introduced into the stomach, it meets 
with common salt and free muriatic acid ; and if its quantity is 
not too great, it is immediately converted into chloride of silver 
— a siibstance absolutely insoluble in pure water. In a solution 
of salt or muriatic acid, however, chloride of silver does dissolve 
in extremely minute quantity ; and it is this small part which 
exercises a medicinal influence when nitrate of silver is ad- 
ministered : the remaining chloride of silver is eliminated from 
the body in the ordinary way. 

Without solubility, or the power of being carried to every part 
of the circulation, no substance possesses activity in reference to 
the animal organism. 

The soluble salts of lead possess many properties in common 
with the salts of silver and mercury ; but all compounds of lead 
with organic matters are capable of decomposition by dilute sul- 
phuric acid. The disease called painter's colicis unknown in all 
manufactories of white lead in which the workmen are accustomed 
to take as a preservative sulphuric acid lemonade (a solution of 
sugar renaered acid by sulphuric acid). 

The organic substances which have combined in the living 
body with metallic oxides or metallic salts, lose their property of 
imbibing water and retaining it, witliout at the same time being 
rendered incapable of permitting liquids to penetrate through their 
pores. A strong contraction and shrinking of the surface is the 
general effect of contact with these metallic bodies. But cor 
roaive sublimate, and several of the salts of lead, possess a pecu. 



INORGANIC POISONS. 363 

liar property, in addition to those already mentioned. When they 
are present in excess, they dissolve the first formed insoluble 
compounds, and thus produce an effect quite the reverse of con- 
traction, namely, a softening of the part of the body on which 
they have acted. 

Salts of oxide of copper, even when in combination with the 
most powerful acids, are reduced by many vegetable substances, 
particularly such as sugar and honey, either into metallic copper, 
or into the red suboxide, neither of which enters into combina- 
tion with animal matter. It is well known that sugar has been 
long employed as the most convenient antidote for pois-.aiing by 
copper. 

With respect to some other poisons, namely, hydrocyanic acid, 
and the organic bases strychnia, brucia, S^-c, we are not acquainted 
with facts calculated to elucidate the nature of their action. Il 
may, however, be presumed with much certainty, thai experi- 
ments upon their mode of action on different animal sujstances 
would very quickly lead to the most satisfactory conclusions re- 
garding the cause of their poisonous effects. 

There is a peculiar class of substances, which are generated 
during certain processes of decomposition, and which act upon 
the animal economy as deadly poisons, not on account of theii 
power of entering into combination with it, or by reason of their 
containing a poisonous material, but solely by virtue of theii 
peculiar condition. 

In order to obtain a clear conception of the mode of action of 
these bodies, it is necessary to call to mind the cause on which 
we have shown the phenomena of fermentation, de^ay, and 
putrefaction to depend. 

This cause may be expressed by the following law, Lng since 
proposed by La Place and Berthollet, although its ti uth with 
respect to chemical phenomena has only lately been proved. " A . 

MOLECULE SET IN MOTION BY ANY POViTER CAN IMPART ITS OWN \\ 
MOTION TO ANOTHER MOLECULE WITH WHICH IT MAY BE W. ■ 
CONTACT." 

This is a law of dynamics, the operation of which is manifest 
in all cases, in which the resistance {force, ajfiinity, or cohesion) 
opposed to the motion is not sufficient to overcome it. 



364 POISONS, CONTAGIONS, MIASMS. 

We have seen that ferment or yeast is a body in the state of 
decomposition, the atoms of which, consequently, are in a state 
of motion or transposition. Yeast placed in contact with sugar 
communicates to the elements of that compound the same state, 
in consequence of which, the constituents of the sugar arrange 
themselves into new and simpler forms, namely, into alcohol and 
carbonic acid. In these new compounds the elements are united 
together by stronger affinities than they were in the sugar, and 
tlierefore under the conditions in which they were produced 
further decomposition is arrested. 

We know, also, that the elements of sugar assume totally dif- 
ferent arrangements, when the substances which excite their 
transposition are in a different state of decomposition from the 
yeast just mentioned. Thus, when sugar is acted on by rennet 
or putrefying vegetable juices, it is not converted into alcohol 
. and carbonic acid, but into lactic acid, mannite, and gum, or into 
I butyric acid. 

Again, it has been shown that yeast added to a solution of pure 
sugar gradually disappears, but that, when added to vegetable 
juices which contain gluten as well as sugar, it is reproduced 
by the decomposition of the former substance. 

The yeast with which these liquids are made to ferment, has 
itself been originally produced from gluten. 

The conversion of gluten into yeast in these vegetable juices 
is dependent on the decomposition (fermentation) of sugar ; for, 
when the sugar has completely disappeared, any gluten still 
remaining in the liquid does not suffer change from contact with 
the newly-deposited yeast, but retains all the characters of 
gluten. 

Yeast is a product of the decomposition of gluten ; but it 
readily passes into a sscond stage of decomposition when in con- 
tact with water. On account of its being in this state of further 
change, yeast excites fermentation in a fresh solution of sugar ; 
and if this second saccharine fluid should contain gluten (should 
it be wort, for example), yeast is again generated, in consequence 
of the transposition of the elements of the sugar exciting a 
similar change in this gluten. 



PUTRID POISONS. 36» 



After this explanation, the idea that yeast reproduces itself, as 
■eeds reproduce seeds, cannot for a moment be entertained. 

From the foregoing facts it follows, that a body in the act of de- 
composition (it may be named the exciter), added to a mixed fluid 
in which its constituents are contained, can reproduce itself in that 
fluid, exactly in the same manner as new yeast is produced 
when yeast is added to saccharine liquids containing gluten. 
This must be more certainly effected when the liquid acted upon 
contains the body by the metamorphosis of which the exciter has 
been originally formed. 

It is also obvious that if the exciter be able to impart its own 
state of transformation to one only of the component parts of the 
mixed liquid acted upon, its own reproduction may be the conse- 
quence of the decomposition of this one body. 

This law may be applied to organic substances forming part 
of the animal organism. We know that all the constituents of 
these ' substances are formed from the blood, and that the blood 
by its nature and constitution is the most complex of all existing 
matters. 

Nature has adapted the blood for the reproduction of everj 
individual part of the organism ; its principal character consists ; 
in its component parts being subordinate to every attraction. ■ 
These are in a perpetual state of change or transformation, which 
is effected in the most various ways through the influence of the 
different organs. 

The blood does not possess the power of causing transforma- 
tions ; on the contrary, its principal character consists in its readily 
suffering transformations ; and no other matter can be compared 
with it in this respect. 

Now it is a well known fact, that when blood, cerebral sub- 
stance, gall, pus, and other substances in a state of putrefaction, 
are laid upon fresh wounds, vomiting, debility, and at length 
death are occasioned. It is also well known that bodies in ana- 
tomical rooms frequently pass into a state of decomposition ca- 
pable of imparting itself to the living body, the smallest cut with 
a knife which has been used in their dissection producing in these 
cases dangerous consequences. 

The poison of bad sausages belongs to this class of noxioua 



366 POISONS, CONTAGIONS, MIASMS. 

substances. Several hundred cases are known in which death 
has occurred from the use of tliis kind of food. In Wiirtemburg 
especially these cases are very frequent, for there the sausages 
are prepared from very various materials. Blood, liver, bacon, 
brains, milk, flour, and bread, are mixed together with salt and 

I spices ; the mixture is then put into bladders or intestines, and 

I after being boiled is smoked. 

When these sausages are well prepared, they may be preserved 
for months, and furnish a nourishing savory food ; but when 
the spices and salt are deficient, and particularly when they are 
smoked too late or not sufficiently, they undergo a peculiar kind 
of putrefaction which begins at the centre of the sausage. 
Without any appreciable escape of gas taking place they become 
paler in color, and more soft and greasy in those parts which 
have undergone putrefaction, and they are found to contain free 
lactic acid, or lactate of ammonia ; products seldom absent from 
putrefying bodies, especially vegetable matter. 

The cause of the poisonous nature of these sausages was as- 
cribed at first to hydrocyanic acid, and afterwards to sebacic acid, . 
although neither of these substances had been detected in them. 
But sebacic acid is no more poisonous than benzoic acid, with 
which it has so many properties in common ; and the symptoms 
produced are sufficient to show that hydrocyanic acid is not the 
poison. 

The death which is the consequence of poisoning by putrefied 
sausages succeeds very lingering and remarkable symptoms. 
There is a gradual wasting of muscular fibre, and of all the con- 
stituents of the body similarly composed ; the patient becomes 
much emaciated, dries to a complete mummy, and finally dies. 
The carcase is stiff" as if frozen, and is not subject to putrefac- 
tion. During the progress of the disease the saliva becomes 
viscous, and acquires an offensive smell. 

Experinxents have been made for the purpose of ascertaining 
the presence of some matter in the sausages, to which their 
poisonous action could be ascribed ; but no such matter has been 
detected. Boiling water and alcohol completely destroy the 
poisonous properties of the sausages, without themselves acquiring 
similar properties. 



PUTRID POISONS. 361 



Now this is the peculiar character of all substances which 
exert an action by virtue of their existing condition — of those 
bodies the elements of which are in a state of decomposition or 
transposition j a state which is destroyed by boiling water and 
alcohol without the cause of the influence being imparted to those 
liquids : for a state of action or power cannot be preserved in a 
liquid. 

Sausages, in the state here described, exercise an action upon 
the organism, in consequence of the stomach and other parts 
with which they come in contact not having the power to arrest 
their decomposition ; and entering the blood in some way or 
other, while still possessing their whole power, they impart their 
peculiar action to the constituents of that fluid. 

The poisonous properties of decayed sausages are not destroy- 
ed by the stomach as those of the small-pox virus are. All the 
substances in the body capable of putrefaction are gradually 
decomposed during the course of the disease, and after death 
nothing remains, except fat, tendons, bones, and a few other sub- 
stances incapable of putrefying in the conditions afforded by the 
body.* 



* In a case of poisoning by sausages, which was communicated to me by 
Herr Salzer, and which occurred )> Sausenbach, near Schw'abischhall, in 
May, 1S42, of all the remedies ttiat were tried sulphuretted hydrogen 
water was found to possess very peculiar efficacy. All the poisoned indi- 
viduals in whom it was tried early enough were saved. In those affected 
by the poison there appeared hoarseness and dryness in the throat, and a 
universal feeling of dryness, constipation without swelling of the abdomen, 
and without perceptible difficulty of breathing ; faintness ; dilated pupil 
v/ith impaired vision ; perfect consciousness and unimpaired motion of all 
the muscles, except those supplied with nerves from the sympathetic sys- 
tem, and rapid putrescence of the dead bodies. The effects were not only 
dependent on the amount of poisoned sausage taken, but also very peculiar 
in each case ; and in one case there was actually no effect, where a large 
quantity of the same sausages had been consumed. In the treatment, the 
sulphuretted hydrogen water decidedly checked the poisonous action : the 
patients first perceived greater ease in swallowing ; then the general 
tension and dryness diminished; the voice, which had been lost, returned; 
the skin became moister, the countenance lighter, and the pressure on the 
eye was relieved. 

Ammonia, diluted so as to be taken as a drink, and at the same time 



368 POISONS, CONTAGIONS, MIASMS. 

It is impossible to mistake the modus operandi of this poiaon, 
for Colin has clearly proved that muscle, urine, cheese, cerebral 
substance, and other matters, in a state of putrefaction, commu- 
nicate their own state of decomposition to substances much 
less prone to change of composition than the blood. When 
placed in contact with a solution of sugar, they cause its putre- 
faction, or the transposition of its elements into carbonic acid and 
alcohol. 

When putrefying muscle or pus is placed upon a fresh wound 
it occasions disease and death. It is obvious that these substances 
communicate their own state of putrefaction to the sound blood 
FROM WHICH THEY WERE PRODUCED, exactly in the same manner 
as gluten in a state of decay or putrefaction causes a similar 
transformation in a solution of sugar. 

Poisons of this kind are even generated by the body itself in 
particular diseases. In small-pox, plague, and syphilis, substances 
of a peculiar nature are formed from the constituents of the 
blood. These matters are capable of inducing in the blood of a 
healthy individual a decomposition similar to that of which they 
themselves are the subjects ; in other words, they produce the 
same disease. The morbid virus appears to reproduce itself just 
as seeds appear to reproduce seeds. 

The mode of action of a morbid virus exhibits such a strong 
similarity to the action of yeast upon liquids containing sugar 
and gluten, that the two processes have been long since compared 
to one another, although merely for the purpose of illustration. 
But when the phenomena attending the action of each respective- 
ly are considered more closely, it will in reality be seen that 
their influence depends upon the same cause. 

In dry air, and in the absence of moisture, all these poisons 
remain for a long time unchanged ; but when exposed to the air 
in the moist condition, they lose very rapidly their peculiar pro 
perties. In the former case, those conditions \re afforded whicl 

rubbed into the skin, afforded relief; but this was only temporary, am, 
there was no improvement observed on continuing this treatment. 

Chlorine diluted with water, and used externally and internally, produce(t 
no improvement : on the contrai-y, the tension and dryness were increased 
so that it soon became necessary to relinquish this treatment. 



MORBID POISONS. 369 



arrest their decomposition without destroyin^r it; in the latter, all 
the circumstances necessary for the completion of their decom- 
position are presented. 

The temperature at which water boils, and contact with alcohol, 
render such poisons inert. Acids, salts of mercury, sulphurous 
acid, chlorine, iodine, bromine, aromatic substances, volatile oils, 
and particularly empyreumatic oils, smoke, and a decoction of 
coffee, completely destroy their contagious properties, in some 
cases combining with them or otherwise effecting their decompo- 
shion. Now all these agents, without exception, retard ferment- 
ation, putrefaction, and decay, and when present in sufficient 
quantity, completely arrest these processes of decomposition. 

A peculiar matter to which the poisonous action is due, cannot, 
we have seen, be extracted from decayed sausages ; and it is 
equally impossible to obtain such a principle from the virus of 
small-pox or plague, and for this reason, that their peculiar 
power is due to an active condition, only recognisable by our 
senses through the phenomena which it produces. 

In order to explain the effects of contagious matters, a peculiar 
principle of life has been ascribed to them — a life similar to 
that possessed by the germ of a seed, which enables it under 
favorable conditions to develope and multiply itself. There cannot 
be a more inaccurate image of these phenomena ; it is one 
which is applicable to contagions, as well as to ferment, to animal 
and vegetable substances in a state of fermentation, putrefaction, 
or decay, and even to a piece of decaying wood, which by mere 
contact with fresh wood, causes the latter to undergo gradually 
the same changes, and become decayed and mouldered. 

If the property possessed by a body of producing such a change 
in any other substance as causes the reproduction of itself, with 
all its properties, be regarded as life, then, indeed, all the above 
phenomena must be ascribed to life. But in that case they must 
not be considered as the only processes due to vitality, for the 
above interpretation of the expression embraces the majority of 
the phenomena which occur in organic chemistry. Life would, 
according to that view, be admitted to exist in every body in 
which chemical forces act. 

If a body A, for example oxamide (a substance scarcely solu- 
17* 



370 POISONS, CONTAGIONS, MIASMS. 

ble in water, and without the slightest taste), be brought into 
contact with another coiTHX)und B, which is to be reproduced ; 
and if this second body be oxalic acid dissolved in water, then 
the following changes are observed to take place : — the oxamide 
is decomposed by the oxalic acid, provided the conditions neces- 
sary for their exercising an action upon one another are p«-esent. 
The elements of water unite with the constituents of oxamide, 
and ammonia is one product formed, and oxalic acid the other, 
both in exactly the proper proportions to combine and form a 
neutral salt. 

Here the contact of oxamide and oxalic acid induces a trans- 
formation of the oxamide, which is decomposed into oxalic acid 
and ammonia. The oxalic acid thus formed, as well as that 
originally added, are neutralized by the ammonia — as far as that 
product suffices to neutralize them ; but, of course, as much free 
oxalic acid exists after the decomposition as before it, and is still 
possessed of its original power. It matters not whether the free 
oxalic acid is that originally added, or that newly produced ; it 
is certain that it has been reproduced in an equal quantity by 
the decomposition. 

If we now add to the same mixture a fresh portion of oxamide, 
exactly equal in quantity to that first used, and treat it in the 
same manner, the same decomposition is repeated ; the free oxalic 
acid enters into combination whilst another portion is liberated. 
In this manner a very minute quantity of oxalic acid may be 
made to effect the decomposition of several hundred pounds of 
oxamide ; and one grain of the acid to reproduce itself in un- 
limited quantity. 

We know that the contact of the virus of small-pox causes 
such a change in the blood, as gives rise to the reproduction of 
the poison from the constituents of the fluid. This transforma- 
tion is not arrested until all the particles of the blood susceptible 
of the decomposition have undergone the metamorphosis. We 
have just seen that the contact of oxalic acid with oxamide caused 
the production of fresh oxalic acid, which in its turn exercised 
the same action on a new portion of oxamide. The transforma- 
tion was only arrested in consequence of the quantity of oxamide 
present bein;^ lirniti^d. In theii- form both the?e transformations 



MORBID POISONS. 371 



belong to the same class ; but although what heie takes place 
exactly corresponds to the definition of life above assumed, no 
unprejudiced mind would admit vitality in either process; since 
they are obviously chemical processes dependent upon the com- 
mon chemical forces. 

The best definition of life involves something more than mere 
reproduction, namely, the idea of an active power exercised by 
VIRTUE OF A DEFINITE FORM, and production and generation in a 
DEFINITE form. By chemical agency we shall some day be able 
to produce the constituents of muscular fibre, skin, and hair ; but 
we cannot form by their means an organized tissue, or an or- 
ganic cell. 

The production of organs, the co-operation of a system of or- 
gans, and their power not only to produce their component parts 
from the food presented to them, but to generate themselves in their 
original form and with all their properties, are characters be- 
longing exclusively to organic life, and constitute a form of 
reproduction independent of chemical powers. 

The chemical forces are subject to the invisible cause by 
which this form is produced. Of the existence of this cause 
itself we are made aware only by the phenomena which it pro- 
duces. Its laws must be investigated just as we investigate 
those of the other powers which effect motion and changes in 
matter. 

The chemical forces are subordinate to this cause of life, just 
as they are to electricity, heat, mechanical motion, and friction. 
By the influence of the latter forces, they suffer changes in their 
direction, an increase or diminution of their intensity, or a com- 
plete cessation or reversal of their action. 

Such an influence and no other is exercised by the vital prin- 
ciple over the chemical forces ; but in every case where com- 
bination or decomposition takes place, chemical affinity and 
cohesion are in action. 

The vital principle is only known to us through the peculiar 
form of its instruments, that is, through the organs in which it 
resides. Hence, whatever kind of energy a substance may 
possess, if it is amorphous and destitute of organs from which the 
impulse of motion or change proceeds, it does not live. Its 



ff 



572 POISONS, CONTAGIONS, MIASMS. 

energy depends in this case on a chemical action. Light, heat, 
fjf electricity, or other influences, may increase, diminish, or arrest 
this action, but they are not its efficient cause. 

In this way the vital principle governs the chemical powers in 
the living body, and this is particularly apparent with regard to 
vegetable life. All those substances to which we apply the 
general name of food, and all the bodies formed from them in the 
organism, are chemical compounds. The vital principle has, 
therefore, no other resistance to overcome, in order to convert 
these substances into component parts of the organism, than the 
chemical powers by which their constituents are held together. 
If the food possessed life, not merely the chemical forces, but this 
vitality, would offer resistance to the vital force of the organism 
it nourished. 

The equilibrium in the chemical attractions of the constituents 
of the food is disturbed by the vital principle of the plant, as we 
know it may be by many other causes. But the union of its ele- 
tnents, so as to produce new combinations and forms, indicates 
jie presence of a peculiar mode of attraction, and the existence 
j)f a power distinct from all other powers of nature, namely, the 
vital principle. 

The vital principle opposes to the continual action of the 
atmospheric moisture and temperature upon the organism, a re- 
sistance which is, up to a certain point, invincible. It is by the 
constant neutralization and renewal of these external influences 
that life and motion are maintained. 

The greatest wonder in the living organism is the fact that an 
unfathomable Wisdom has made the cause of a continual decom- 
position or destruction, naaiely, the support of the process of re- 
spiration, to be the means of renewing the organism, and of 
resisting all the other atmospheric influences, such as those of 
moisture and changes of temperature. 

When a chemical compound of simple constitution is introduced 
into the stomach, or any other part of the organism, it must ex- 
ercise a chemical action upon all substances with which it comes 
in contact ; for we know the peculiar character of such a bod}- 
to be an aptitude and power to enter into combinations and elfcct 
deoonnpositions. 



THEIR MODE OF ACTION. 373 

The chemical action of such a compound is, of course, opposed 
by the vital principle. The results produced depend upon the 
strength of their respective actions ; either an equilibrium of both 
powers is attained, a change being effected without the destruction 
of the vital principle, in which case A medicinal effect is occa- 
sioned ; or the acting body yields to the superior force of vitality, 
that is, IT IS DIGESTED ; or, lastly, the chemical action obtains the 
ascendency, and it acts as a poison. 

Every substance may be considered as nutriment which loses 
its former properties when acted on by the vital principle, and 
does not exercise a chemical action upon the living organ. 

Another class of bodies change the direction, the strength, 
and intensity of the resisting force (the vital principle), and 
thus exert a modifying influence upon the functions of its or- 
gans. They produce a disturbance in the system, either by 
their presence, or by themselves undergoing a change ; these are 

MEDICAMENTS. 

A third class of compounds are called poisons, when they pos- 
sess the property of uniting with organs or with their component 
parts, and when their power of effecting this is stronger than the 
resistance offered by the vital principle. 

The quantity of a substance and its condition must obviously 
completely change the mode of its chemical action. 

Increase of quantity is known to be equivalent to superior 
affinity. Hence a medicament administered in excessive quan- 
tity may act as a poison, and a poison in small doses as a 
viedicament. 

Food will act as a poison, that is, it will produce disease, when 
it is able to exercise a chemical action by virtue of its quantity ; 
or when either its condition or its presence retards, prevents, or 
arrests the motion of any organ. 

A compound acts as a poison when all the parts of an organ 
with which it is brought into contact enter into chemical combi- 
nation with it, while it may operate as a medicine when it pro- 
duces only a partial change. • 

No other component part of the organism can be compared to 
the blood, in respect of the feeble resistance which it olfers to 
exterior influences. The blood is not an organ which is formed, 



J74 POISONS, CONTAGIONS, MIASMS. 

but an organ in the act ot" formation ; indeed, it is the sum of all 
the organs which are being formed. The chemical force and the 
vital principle hold each other in such perfect equilibrium, that 
every disturbance, however trifling, or from whatever cause it 
may proceed, efl'ects a change in the blood. This liquid possesses 
so little of permanence that it cannot be removed from the body 
without immediately suffering a change, and cannot come in 
contact with any organ in the body, without yielding to its 
attraction. 

The slightest action of a chemical agent upon the blood ex- 
ercises an injurious influence ; even the momentary contact with 
the air in the lungs, although effected through the medium of 
cells and membranes, alters the color and other qualities of the 
blood. Every chemical action propagates itself through the mass 
of the blood ; for example, the active chemical condition of the 
constituents of a body undergoing decomposition, fermentation, 
putrefaction, or decay, disturbs the equilibrium between the 
chemical force and the vital principle in the circulating fluid, and 
overcomes the latter. Numerous modifications in the composition 
and condition of the compounds produced from the elements of 
the blood, result from the conflict of the vital force with 
chemical affinity, in their incessant endeavor to overcome one 
another. 

All the characters of the phenomena of contagion tend to dis- 
prove the existence of vitality in contagious matters. They 
without doubt exercise an influence very similar to some pro- 
cesses in the living organism ; but the cause of this influence is 
chemical action, which is capable of being subdued by other 
chemical actions, by opposed agencies. 

Several of the poisons generated in the body by disease lose all 
their power when introduced into the stomach, but others are not 
thus destroyed. 

It is a fact very decisive of their chemical nature and mode 
of action, that those poisons which are neutral or alkaline, such 
as the poisonous matter of the contagious fever in cattle (fi/phus 
c':titiagios7(s rmiiinanUum), or that of the small-pox, lose their 
*vhnle power of contagion in the stomach ; whilst that of sausa- 



THEIR MODE OF ACTION. 379 



ges, which has an acid reaction, retains all its frightful properties 
under the same circumstances. 

In the former of these cases, the free acid present in the 
itomach destroys the action of the poison, the chemical properties 
of which are opposed to it ; whilst in the latter it strengthens, or 
at all events does not offer any impediment to poisonous action. 

Microscopical examination has detected peculiar bodies resem- 
bling the globules of the blood in malignant putrefying pus, in 
the matter of vaccine, dsc. The presence of these bodies has 
given weight to the opinion, that contagion proceeds from the 
development of a diseased organic life ; and these formations 
have been regarded as the living seeds of disease. 

This view, which does not admit of discussion, has led those 
philosophers who are accustomed to search for explanations of 
phenomena in forms, to consider the yeast produced by the fer- 
mentation of beer as possessed of life. They have imagined it 
to be composed of animals or plants, which nourish themselves 
from the sugar in which they are placed, and at the same time 
yield alcohol and carbonic acid as excrementitious matters.* 

It would perhaps appear wonderful if bodies, possessing a 
crystalline structure and geometrical figure, were formed during 
the processes of fermentation and putrefaction from the organic 
substances and tissues of organs. We know, on the contrary, 
that the complete dissolution into organic compounds is preceded 
by a series of transformations, in which the organic structures 
gradually resign their forms. 

Blood, in a state of decomposition, may appear to the eye un- 
changed ; and when we recognise the globules of blood in a 
liquid contagious matter, the utmost that we can thence infer is, 
that those globules have taken no part in the process of decom- 
position. All the phosphate of lime may be removed from bones, 
leaving them transparent and flexible like leather, without the 
form of the bones being in the smallest degree lost. Again : 
bones may be burned until they be quite white, and consist 
merely of a skeleton of phosphate of lime, but they will stilJ 
possess their original form. In the same way processes of de^ 

* Annalen der Pharmacie, Band xxix., S. 93 und 100. 



376 POISONS, CONTAGIONS, MIASMS. 

composition in the blood may affect individual constituents only 
of that fluid, which will become destroyed and disappear, whilst 
its other parts will maintain the original form. 

Several kinds of contagion are propagated through the air : so 
that according to the view already mentioned, we must ascribe 
life to a gas, that is, to an aeriform body. 

All the supposed proofs of the vitality of contagions are 
merely ideas and figurative representations, fitted to render the 
phenomena more easy of apprehension by our senses, without 
explaining them. These figurative expressions, with which we 
are so willingly and easily satisfied in all sciences, are the foes 
of all inquiries into the mysteries of nature ; they are like the 
fata morgana, which show us deceitful views of seas, fertile fields, 
and luscious fruits, but leave us languishing when we have most 
need of what they promise. 

It is certain that the action of contagions is the result of a pe- 
culiar influence dependent on chemical forces, and in no way 
connected with the vital principle. This influence is destroyed 
by chemical actions, and manifests itself wherever it is not sub- 
dued by some antagonist power. Its existence is recognised in a 
connected series of changes and transformations, in which it 
causes all substances capable of undergoing similar changes to 
participate. 

An animal substance in the act of decomposition, or a sub- 
stance generated from the component parts of a living body by 
disease, communicates its own condition to all parts of the system 
capable of entering into the same state, if no cause exist in 
ihese parts by which the change is counteracted or destroyed. 

Disease is thus excited by contagion. 

The transformations produced by the disease assume a series 
of forms. 

In order to obtain a clear conception of these transformations, 
we may consider the changes which substances, more simply 
composed than the living body, suffer from the influence of simi- 
lar causes. When putrefying blood or yeast in the act of trans- 
foimation is placed in contact with a solution of sugar, the ele- 
ments of the latter substance are transposed, so as to form alcohol 
and carbonic acid. 



THEIR MODE OF ACTION. S'^l 

A piece of the re-nnet-stomach of a calf in a state of decoin[K»- 
sition occasions the elements of sugar to assume a different 
arrangement. The sugar is converted mto lactic acid without 
the addition or loss of any element. One atom of sugar of 
grapes Cjj Hjj O^^ yields two atoms of lactic acid = 2 (Cg 
H, O, ). 

When the juice of onions or of beet-root is made to ferment at 
high temperatures, lactic acid, mannite, and gum are formed. 
Thus, according to the different states of the transposition of the 
elements of the exciting body, the elements of the sugar arrange 
themselves in different manners, that is, different products are 
formed. 

The immediate contact of the decomposing substance with the 
sugar is the cause by which its particles are made to assume new 
forms and natures. The removal of that substance occasions 
the cessation of the decomposition of the sugar, so that should 
its transformation be completed before the sugar, the latter can 
suffer no further change. 

In none of these processes of decomposition is the exciting 
body reproduced ; for the conditions necessary to its reproduction 
do not exist in the elements of the sugar. 

Just as yeast, putrefying flesh, and the stomach of a calf in a 
state of decomposition, when introduced into solutions of sugar, 
effect the transformation of this substance, without being them- 
selves regenerated ; in the same manner, miasms and certaii? 
contagious matters produce diseases in the human organism, by 
communicating the state of decomposition, of which thej^ them- 
selves are the subject, to certain parts of the organism, without 
themselves being reproduced in their peculiar form and nature 
during the progress of the decomposition. 

The disease in this case is not contagious. 

But, when yeast is introduced into a mixed liquid containing 
both sugar and gluten, such as wort, the act of decomposition of 
the sugar effects a change in the form and nature of the gluten, 
which is, in consequence, also subjected to transformation. As 
\oni as some of the fermenting sugar remains, gluten continues 
to be separated as yeast, and this new matter in its turn excites 
fermentation in a fresh solution of sugar or wort. If the sugar, 



37S POISONS, CONTAGIONS, MIASMS. 



however, should be first decomposed, the gluten remaining in so 
lution is not converted into yeast. We see, therefore, that the 
reproduction of the exciting body or ferment here depends — 

1. Upon the presence of that substance from which it was 
originally formed ; 

2. Upon the presence of a compound capable of being decom- 
posed by contact with the exciting body. 

If we express in the same terms the reproduction of conta- 
gious matter in contagious diseases, since it is quite certain that 
they must have their origin in the blood, we must admit that the 
blood of a healthy individual contains substances, by the decom- 
position of which the exciting body or contagion can be produced. 
It must further be admitted, when contagion results, that the 
blood contains a second constituent capable of being decom- 
posed by the exciting body. It is only in consequence of the 
transformation of the second constituent, that the original exciting 
body can be reproduced. 

A susceptibility of contagion indicates the presence of a 
certain quantity of this second body in the blood of a healthy 
individual. The susceptibility for the disease and its intensity 
must augment according to the quantity of that body present in 
the blood ; and in proportion to its diminution or disappearance, 
the coui'se of the disease will change. 

When a quantity, however small, of contagious matter, 
that is of the exciting body, is introduced into the blood of a 
healthy individual, it will be again generated in the blood, 
just as yeast is reproduced from wort. Its condition of trans- 
formation will be communicated to a constituent of the 'blood ; 
and in consequence of the transformation suffered bv this 
substance, a body identical with or similar to the exciting or 
contagious matter will be produced from another constituent 
substance of the blood. The quantity of the exciting body 
newly produced must constantly augment, if its further trans- 
formation or decomposition p -oceeds more slowly than that of 
the compound in ths blood, the decomposition of which it 
effects. 

If the transformation of the yeast generated in tlie fermen- 
tation of wort proceeded with the same rapidity as that of the 



THEIR MODE OF ACTION. S75 



particles of the sugar contained in it, both would sim il- 
taneously disappear when the fermentation was completed. 
But yeast requires a much longer time for decomposition 
than sugar, so that after the latter has completely disappeared, 
there remains a much larger quantity of yeast than existed 
in the fluid at the commencement of the fermentation, — yeasl; 
which is still in a state of incessant progressive transformation, 
and therefore possessed of all its peculiar properties. 

The state of change or decomposition which affects one particle 
of blood, is imparted to a second, a third, and at last to all tne 
particles of blood in the whole body. It is communicated in 
like manner to the blood of another individual, to that of a third 
person, and so on — or, in other words, the disease is excited in 
them also. 

It is quite certain that a number of peculiar substances 
exist in the blood of different men, in that of the same 
man at different periods of his development, and in that of 
animals. 

The blood of the same individual contains, in childhood and 
youth, variable quantities of substances, which are absent from 
it in no other stages of growth. The susceptibility of contagion 
by peculiar exciting bodies in childhood, indicates a propagation 
and regeneration of the exciting bodies, in consequence of tha 
transformation of certain substances present in the blood, and 
in the absence of which no contagion would ensue. The form 
of a disease is termed benignant, when the transformatims 
OF TWO constituents of the body not essential to life, are simul- 
taneously completed without the other parts taking a share in 
the decomposition ; it is termed malignant when they affrct 
essential organs. 

It cannot be supposed that the different changes in the 
substance of the existing organs, by which their constituents are 
converted into fat, muscular fibre, substance of the brain and 
nerves, bones, hair, &c., and the transformation of food into 
blood, can take place without the simultaneous formation of new 
compounds which require to be removed from the body by the 
organs of excretion. 

In an adult these excretions do not vary much either ir. ;.'.eir 



380 POISONS, CONTAGIONS, ML.SMS. 

nature or quantity. The food taken is not employed in increas- 
ing the size of the body, but merely for the purpose of replacing 
any substances which may be consumed by the various actions 
in the organism ; every motion, every manifestation of organic 
properties, and every organic action being attended by a change 
in the material of the body, and by the assumption of a new form 
by its constituents.* 

But in a child this normal condition of sustenance is accom- 
panied by an abnormal condition of growth, and increase in the 
size of the body, and of each individual part of it. Hence, 
there must be a much larger quantity of foreign substances, not 
belonging to the organism, diffused through every part of the 
blood in the body of a young individual. 

When the organs of secretion are in pi'oper action, these 
oubstances will be removed from the system ; but when the 

■ functions of those organs are impeded, they will remain in 
the blood, or become accumulated in particular parts of the 
body. The skin, lungs, and other organs, assume the functions 
of the diseased secreting organs, and the accumulated substances 
are eliminated by them. If, when thus exhaled, these sub- 
stances happen to be in the state of progressive transformation, 
they are contagious ; that is, they are able to produce the 
same state of disease in another healthy organism, provided the 
latter organism is susceptible of their action — or, in other words, 
contains a matter capable of suffering the same process of 
decomposition. 

The production of matters of this kind, which render the body 
susceptible of contagion, may be occasioned by the manner of 
living, or by the nutriment taken by an individual. A super- 
abundance of strong and otherwise wholesome food may produce 
them, as well as a deficiency of nutriment, uncleanliness, or 
even the use of decayed substances as food. 

* The experiments of Barruel upon the different odors emitted from 
blood on the aildition uf sulphuric acid, prove that peculiar substances are 

■ contained in the lilood of different individuals ; the hlood of a man of a fair 
complexion and that of a man of dark complexion were found to yield dif- 
ferent odors ; the blood of animals also differed in this respect very per- 
C'.'ptibly from that of man. 



THEIR MODE OF ACTION. 3S1 

All these conditions for contagion must be considered as acci- 
dental. Their formation and accumulation in the body may be 
prevented, and they may even be removed from it without dis- 
turbing its most important functions or health. Their presence 
is not necessary to life. 

The action, as well as the generation of the matter of conta- 
gion is, according to this view, a chemical process participated 
in by all substances in the living body, and by all the constitu- 
ents of those organs in which the vital principle does not over- 
come the chemical action. The contagion, accordingly, either 
spreads itself over every part of the body, or is confined particu- 
larly to certain organs, that is, the disease attacks all the organs, 
or only a few of them, according to the feebleness or intensity 
of their resistance. 

In the abstract chemical sense, reproduction of a contagion 
depends upon the presence of two substances, one of which 
becomes completely decomposed, but communicates its own 
state of transformation to the second. The second substance 
thus thrown into a state of decomposition is the newly-formed 
contagion. 

The second substance must have been originally a con- 
stituent of the blood : the first may be a body accidentally 
present : but it may also be a matter necessary to life. If both 
be constituents indispensable for the support of the vital func- 
tions of certain principal organs, daath is the consequence of 
their ti'ansformation. But if the absence of the one substance 
which was a constituent of the blood do not cause an immediate 
cessation of the functions of the most important organs, if they 
continue in their action, although in an abnormal condition, 
convalescence ensues. In this case the products of the trans- 
formations still existing in the blood are used for assimila- 
tion, and at this period secretions of a peculiar nature are 
produced. 

When the constituent removed from the blood is a product of 
an unnatural manner of living, or when its formation takes place 
only at a certain age, the susceptibility of contagion ceases upon 
its disappearance. 

The eflfects of vaccine matter indicate that an accidental con 



AS2 POISONS, CONTAGIONS, MIASMS. 

stituent of the blood is destroyed by a peculiar process of decom- 
position, which does not alTect the other constituents of the circu- 
lating fluid. 

If the manner in which the precipitated yeast of Bavarian beer 
acts be called to mind, the modus operandi of vaccine lymph can 
scarcely be matter of doubt. 

Both the kind of yeast here referred to and the ordinary 
ferment are formed from gluten, just as the vaccine virus and 
the matter of small-pox are produced from the blood. Ordinary 
yeast and the virus of human small-pox, however, effect a 
violent tumultuous transformation, the former in vegetable 
juices, the latter in blood, in both of which fluids respectively 
their constituents are contained, and they are reproduced from 
these fluids with all their characteristic properties. The preci- 
pitated yeast of Bavarian beer, on the other hand, acts entirely 
upon the sugar of the fermenting liquid, and occasions a very 
protracted decomposition of it, in which the gluten which is 
also present takes no part. But the air exercises an influence 
upon the latter substance, and causes it to assume a new form 
and nature, in consequence of which this kind of yeast also is 
reproduced. 

The action of the virus of cow-pox is analogous to that of the 
low yeast ; it communicates its own state of decomposition to a 
matter in the blood, and from a second matter is itself regene- 
rated, bul by a totally different mode of decomposition ; the pro- 
duct possesses the mild form, and all the properties of the lymph 
of cow-pox. 

The susceptibility of infection by the virus of human small- 
pox must cease after vaccination, for the substance to the pre- 
sence of which this susceptibility is owing has been removed 
from the body by a peculiar process of decomposition artificially 
excited. But this substance may be again generated in the same 
individual, so that he may again become liable to contagion ; and 
a second or third vaccination will again remove the peculiar sub- 
stance from the system. 

Chemical actions are propagated in no organs so easily as in 
the lungs ; and it is well known that diseases of the lungs are, 
9lx>ve all others, frequent and dangerous. 



THEIR MODE OF ACTION. ^3 

If it is assumed that chemical action and the vital principle 
mutually balance each other in the blood, it must further be sup- 
posed that the chemical powers will have a certain degree 
of preponderance in the lungs, where the air and blood are in 
immediate contact ; for these organs are iitted by nature to favor 
chemical action ; they do not offer resistance to the change? 
experienced by the venous blood. 

The contact of air with venous blood is limited to a very short 
period of time by the motion of the heart, and any change beyond 
a determinate point is, in a certain degree, prevented by the 
rapid removal of the blood which has become arterialized. Any 
disturbance in the functions of the heart, and any chemical 
action from without, even though weak, occasions a change in 
the process of respiration. Solid substances, also, such as dust 
from vegetable, animal, or inorganic bodies, act in the same way 
as they do in a saturated solution of a salt in the act of crystal- 
lization, that is, they occasion a deposition of solid matters from 
the blood, by which the action of the air upon the latter is altered 
or prevented. 

When gaseous and decomposing substances, or those which 
exercise a chemical action, such as sulphuretted h}'drogen and 
carbonic acid, obtain access to the lungs, they meet with less 
resistance in this organ than in any other. The chemical j)ro- 
cess of slow combustion in the lungs is accelerated by all sub- 
stances in a state of decay or putrefaction, by ammonia and !,ll<a- 
lies ; but is retarded by empyreumatic substances, volatile oils. 
and acids. Sulphuretted hydrogen produces immediate decom- 
position of the blood, and sulphurous acid combines with the 
substance of the tissues, the cells, and membranes. 

When the process of respiration is modified by contact with a 
matter in the progress of decay, when this matter communicates 
the state of decomposition, of which it is the subject, to the blood, 
disease is produced. 

If the matter undergoing decomposition is the product of a dis- 
ease, it is called contagion ; but if it is the product of the decay 
or putrefaction of animal and vegetable substances, or if it acts 
by its chemical properties (not by the state in which it is), and 



384 POISONS, CONTAGIONS, MIASMS. 

therefore enters into combination with parts of the body, or causes 
their decomposition, it is termed miasm. 

Gaseous contagious matter is a miasm emitted from blood, and 
capable of generating itself again in living blood. 

But miasm, properly so called, causes disease without being 
itself reproduced. 

All the observations hitherto made upon gaseous contagious 
matters prove, that they also are substances in a state of decom- 
position. When vessels filled with ice are placed m air impreg- 
nated with gaseous contagious matter, their outer surfaces 
become covered with water containing a certain quantity of this 
matter in solution. This water soon becomes turbid, and, in 
common language, putrefies, or, to describe the change more 
correctly, the process of decomposition of the dissolved contagious 
matter is completed in the water. 

All gases emitted from putrefying animal and vegeiable sub- 
stances in processes of disease, generally possess a peculiar 
nauseous offensive smell, a circumstance which, in most cases, 
proves the presence of a body in a state of decomposition, that is, 
of chemical action. Smell itself may, in many cases, be con- 
sidered as a reaction of the nerves of smell, or as a resistance 
offered by the vital powers to chemical action. 

Many metals emit a peculiar odor when rubbed, but this is the 
case with none of the noble metals,' — those which suffer no 
change when exposed to air and moisture. Arsenic, phos- 
phorus, musk, the oil of linseed, lemons, turpentine, rue, and 
peppermint, possess an odor only when they are in the act 
of eremacausis (oxidation at common temperatures). 

The odor of gaseous contagious matters is owing to the same 
cause ; but it is also generally accompanied by ammonia, which 
may be considered, in many cases, as the means through which 
the contagious matter receives a gaseous form, just as it is the 
means of causing the smell of innumerable substances of little 
volatility, and of many which have no odor. (Robiquct.)* 

Ammonia is very generally produced in cases of disease ; it is 
always emitted in those in which contagion is generated, and is 

* Ann. de Chim. et de Phys., XV., 27. 



THEIR MODE OF ACTION. 385 

an invariable product of the decomposition of animal matter. 
The presence of amnKXiia in the air of chambers in which dis- 
eased patients lie, pai'ticularly of those afflicted with a contairious 
disease, may he readily detected ; for the moisture condensed by 
ice in the manner just described, produces a white precipitate in 
a solution of corrosive sublimate, just as a solution of ammonia 
does. The ammoniacal salts, also, obtained by the evaporation 
of rain-water after an acid has been added, when treated with 
hme so as to set free their ammonia, emit an odor most closely 
resembling that of corpses, or the peculiar smell of dunghills. 

By evaporating acids in air containing gaseous contagions, the 
ammonia is neutralized, and we thus prevent further decomposi- 
tion, and destroy the power of the contagion, that is, its state of 
chemical change. Muriatic and acetic acids, and, in several 
cases, nitric acid, are to be preferred for this purpose before all 
others. Chlorine, also, is a substance which destroys ammonia 
and organic bodies with much facility ; but it exerts such an 
injurious influence upon the lungs, that it may be classed 
amongst the most poisonous bodies known, and should never be 
employed in places in which men breathe. 

Carbonic acid and sulphuretted hydrogen, which are fre- 
quently evolved from the earth in cellars, mines, wells, sewers, 
and other places, are amongst the most pernicious miasms. The 
former may be removed from the air by alkalies ; the latter, by 
burning sulphur (sulphurous acid), or by the evaporation of nitric 
acid. 

The characters of many organic compounds are well worthy 
of the attention and study both of physiologists and pathologists, 
more especially in relation to the mode of action of medicines 
and poisons. 

Several of such compounds are known, which to all appear- 
ance are quite indifferent substances, and yet cannot be brought 
into contact with one another in water without suffering a com- 
plete transformation. All substances which thus suffer a mutual 
decomposition, possess complex atoms ; they belong to the highest 
order of chemical compounds. For example, amygdalin, n con- 
stituent of bitter almonds, is a perfectly neutral body, of a slightly 
bitter taste, and very easily soluble in water. But when it is 
18 



386 POISONS, CONTAGIONS, MIASMS 



introduced into a watery solution of synaptas (a constituent of 
sweet almonds), it disappears completely without the disengage, 
ment of any gas, and the water is found to contain free hydro- 
cyanic acid, hydruret of benzule (oil of bitter almonds), a pecu- 
liar acid and sugar, all substances of which merely the elements 
existed in the amygdalin. The same decomposition is effected 
when bitter almonds, which contain the same white matter as the 
sweet, are rubbed into a powder and moistened with water. 
Plence it happens that bitter almonds, pounded and digested in 
alcohol, do not yield oil of bitter almonds containing hydrocyanic 
acid, by distillation with water ; for the substance which occa- 
sions the formation of those volatile substances, is dissolved by 
alcohol without change, and is therefore extracted from the 
pounded almonds. Pounded bitter almonds do not contain 
amygdalin, after having been moistened with water, for that sub- 
stance is completely decomposed when they are thus treated. 

Volatile compounds cannot be detected by their smell in the 
seeds of the Sinapis alba and S. nigra. A fixed oil of a mild 
taste is obtained from them by pressure, but no trace of a volatile 
substance. If, however, the seeds are rubbed to a fine powder, 
and subjected to distillation with warer, a volatile oil of a very 
pungent taste and smell passes ovei along with the steam. But 
if, on the contrary, the seeds are tre;)ted with alcohol previously 
to their distillation with water, the residue does not yield a vola- 
tile oil. The alcohol contains a crysialline body called sinapin, 
and several other bodies. These do not possess the cliaracteristic 
pungency of the oil, but it is by the contact of them with water, 
and with the albuminous constituents of the seeds, that the vola- 
tile oil is formed. 

Thus bodies which would be regarded as absolutely indifTerent 
in inorganic chemistry, on account of their possessing no promi- 
nent chemical characters, when placed in contact with one 
another, are mutually decomposed. Their constituents arrange 
themselves in a peculiar manner, so as to form new combina- 
tions ; a complex atom dividing into two or more atoms of les3 
complex constitution, in consequence of a mere disturbance in 
the attraction of their elements. 

The white constituents of the almonds and mustard, which 



THEIR MODE OF ACTION. 3S1 

resemble coagulated albumen, must be in a peculiar state, in 
order to exert their action upon amygdalin, and upon those con- 
stituents of mustard from which the volatile pungen? jil is 
produced. If almonds, after being blanched and pounded, are 
thrown into boilinjr water, or treated with hot alcohol, with 
mineral acids, or -vjch salts of mercury, their power to effect a 
decomposition in amygdalin is completely destroyed. Synaptas 
is an azotized body which cannot be preserved when dissolved in 
water. Its solution becomes rapidly turbid, deposits a white pre- 
cipitate, and acquires the offensive smell of putrefying bodies. 

It is exceedingly probable that the peculiar state of transposi- 
tion into which the elements of synaptas are thrown when dis- 
solved in water, may be the cause of the decomposition of amyg- 
dalin, and formation of the new products arising from it. The 
action of synaptas, in this respect, is very similar to that of rennet 
upon sugar. 

Malt, and the germinating seeds of corn in general, contain a 
substance called diastase, which is formed from the gluten con- 
tained in them, and cannot be brought in contact with starch and 
water without effecting a change in the starch. 

When bruised malt is strewed upon warm paste of starch, the 
paste, after a few minutes, becomes quite liquid, and the water 
is found to C'iUtain, in place of starch, a substance in many 
respects similar to gum. But when more malt is added, and the 
heat longer continued, the liquid acquires a sweet taste, and all 
the starch is found to be converted into sugar of grapes. 

The elements of diastase have at the same time arranged 
themselves into new combinations. 

The conversion of the starch contained in food into sugar of 
grapes, in diabetes mellitus, indicates that amongst the constitu- 
ents of some one organ of the body a substance or substances 
exist in a state of chemical action, to which the vital principle of 
the diseased organ does not oppose iesistance. The componcn'. 
parts of the organ must suffer changes simultaneously with the 
starch, so that the more starch is furnished to it, the more ener- 
getic and intense the disease must become ; while if only food 
incapable of suffering such transformation from the same cause 
.8 supplied, and the vital energy is strengthened by stimulant 



388 POISONS, CONTAGIONS, MIASMS. 

remedies and strong nourishment, the chemical action may finally 
be subdued, or, in other words, the disease cured. 
^ The conversion of starch into sugar may also be effected by 
^■i, pure gluten, and by dilute mineral acids. 

From all t!ie preceding facts, we see that very various trans- 
posiiions, and changes of composition and properties, may be 
produced in complex organic molecules, by every cause which 
occasions a disturbance in the attraction of their elements. 

When moist copper is exposed to air containing carbonic acid, 
the contact of this acid increases the affinity of the metal for the 
oxygen of the air in so great a degree that they combine, and 
the surface of the copper becomes covered with green carbonate 
of copper. Two bodies which possess the power of combining 
together, assume, however, opposite electric conditions at the 
moment in which they con}e in contact. 

When copper is placed in contact with iron, a peculiar electric 
condition is excited, in consequence of which the property of the 
copper to unite with oxygen is destroyed, and the metal remains 
quite bright. 

When formate of ammonia is exposed to a temperature of 
388° F. (180° C), the intensity and direction of the chemical 
force undergo a change, and the conditions under which the ele- 
ments of this compound are enabled to remain in the same form 
cease to be present. The elements, therefore, arrange them- 
selves in a new form ; hydrocyanic acid and water being the 
results of the change. 

Mechanical motion, friction, or agitation, is sufficient to cause 
a new disposition of the constituents of fulminating silver and 
mercury, that is, to effect another arrangement of their elements, 
or to cause the production of new compounds in a liquid.- 

We know that electricity and heat possess a decided influence 
' I upon the exercise of chemical affinity ; and that the attractions 
of substances for one another are subordinate to numerou.s causes 
which change the condition of these substances by altering the 
direction of their attractions. In the same manner, therefore, the 
exercise of chemical powers in tlie living organism is dependent 
upon the vital principle. 

The power of elements to unite together, and to form thf 



THEIR MODE OF ACTION. 389 

peculiar compounds, which are generated in animals and vegeta- 
bles, is chemical affinity ,* but the cause by which they are pre 
vented from ai'ranging themselves according to the degrees of 
their natural attractions — the cause, therefore, by wliich they are 
made to assume their peculiar order and form in the body, is the 
vital principle. 

After the removal of the cause which produced their union — 
that is, after the extinction of life — most organic atoms retain 
their condition, form, and nature, only by a vis inertice ; for a 
great law of nature proves that matter does not possess the power 
of spontaneous action. A body in motion loses its motion only 
when a resistance is opposed to it : and a body at rest cannot be 
put in motion, or into any action whatever, without the operation 
of some exterior cause. 

The same numerous causes which are opposed to the forma- 
tion of complex organic molecules, under ordinary circumstances, 
occasion their decomposition and transformations when the only 
antagonist power, the vital principle, no longer counteracts the 
influence of those causes. Contact with air and the most feeble 
chemical action now effect changes in the complex molecules ; 
even contact with any body, the particles of which are under- 
going motion or transposition, is often sufficient to destroy their 
state of rest, and to disturb their statical equilibrium in the 
attractions of their constituent elements. An immediate con- 
sequence of this is, that they arrange themselves according to the 
different degrees of their mutual attractions, and that new com- 
pounds are formed, in which chemical affinity has the ascendency; 
and opposes any further change, as long as the conditions undol 
which these compounds were formed remain unaltered. 



APPENDIX TO PART II. 



Some potatoes, which had been wrapped in several folds of paper, 
placed in a box, and kept in a dark but moderately warm place 
in the laboratory, were found in March to be enveloped in a kind 
of net, formed of sprouts of two lines in thickness, and 10 to 15 
inches in length. On these sprouts there were several hundred 
small tubers, of -^ to -J- of an inch in thickness. The sprouts and 
the tubers possessed a white color, and did not exhibit any signs of 
leaves. On examining the parent potatoe with a microscope, it 
was found that its exterior cells were still partly filled with 
granules of starch ; but the interior was quite empty, and its 
substance soft and elastic. The sprouts and the cells of the 
young potatoes abounded in starch. 

The growth of these sprouts, and the formation of the tubers 
at the expense of the constituents of the potatoes, give a good 
illustration of the formation and nutrition of fungi. The organic 
substance present in the potatoe obtains a new form by means of 
the active power resident in the germ ; for, in this case, it cannot 
be supposed that the food was extracted from the air. Now, just 
as the constituents of the old potatoe entered into, and were again 
found unchanged in the sprouts of the young ones, in like man- 
ner animal and vegetable substances in a state of decay enter 
into the fungi arising from them. Thus the ingredients of these 
bodies, as the products of iheir putrefaction, pass over into the 
fungi, exactly as the interior substance of the parent potatoe enters 
into the sprouts and young tubers. For this conversion organic 



392 APPENDIX. 



power alone is sufficient, and light and other conditions of vege- 
table life may be entirely excluded. 



TABLE 

SHOWING THE PROPORTION BETWEEIV THE ENGLISH ATiD HESSIAIJ 
STANDARD OF WEIGHTS AND MEASURES, 

1 lb. English is equal to 0"90719 lbs. Hessian. 

1 Hessian acre is equal to 26,910 English square feet. 

1 English square foot is equal to 1"4S64 Hessian square feet. 

1 English cubic foot contains r81218 of a Hessian cubic foot 



INDEX. 



A. 
Absorption, by roots, 64 

Of salts, 7-2 
Acid, acetic, transformation of, 2S0 

P'ormation of, 302-310 

Boracic, 77 

Carbonic, 3 

contained in the atmo- 
sphere, 14 

decomposed by plants, 15 

disintegrates rocks, 113 

is furnished by humus, 29 

is expired by animals, 16 

is a product of decay, 299 

why necessary to plants, 64 

Cyanic, S4 

Formic, 41 
Hippuric, 49 
Humic, 5 

properties of, 5 

contains ammonia, 6 

Hydrocyanic, 266 

Kinic, 71 

Meconic, 71 

Melanic, 29S 

Nitric, 214, 306 

Phosphoric, in ashes of plants, 

116 
Rocellic, in plants, 65 
Succinic, 343 
Sulphuric, a source of sulphur, 

60 

retains amm.onia, 181 

action on soils, IS 3 

Acids, action of, upon sugar, 278 
Arrest decny, 2'JO 
Capacity of saturation, 6t> 
Organic, in plants, 3, 65 

how formed, 13S 

essential to formation of 

sugar, 137 



Agave America >rX, absorbs oxy 

gen, 22 
Agriculture, object of, 108 

How attained, lOS 

Its importance, 107 

A principle in, 179 

Science necessary to, 124 
Air, access of, favored, 29 

Ammonia in, 43 

Carbonic acid in, 14 

Effect of upon juices, 302 

— = — on soils, 82 

Improved by plants, 16 

Necessary to respiration, 167 

to plants, 96 

Nitric acid contained in, 218 
Albumen, 58, 134 
Alcohol, effect of heat on, 2S1 

Products of its oxidation, 299 

From sugar, 237 
Alkalies, contained in soils, 83, 92, 
111 

Essential to the formation of 
sugar, starch, and gum, 187 

Necessity for restoring to soils, 
113 

Promotes decay of wood, 341 

Quantity of in aluminous mine- 
rals, ill 

Use of in phnts, 121 
Alk.ali!Vs Bases, in plants, on what 
their existence depen:is, 70 

Gaits in plants, sources of, 114 

contained in fertile soils, 

114 

• liberated from soils, by tbt 

action of air and of lime, 128 
Alloxan, 3^4 
Alloxantin, 507 
Alumina, in fertile soils, 110 

its influence on vegetation, 11) 



304 



INDEX. 



Ammonia, carbonate of, in air, 43 

How fixed, ISl 

Cause of nitrification, 309 

Changes colors, 41 

Condensed by charcoal, 50 

Conversion of, into nitric acid, 
30'J 

Early existence of, 206 

Evolved from manure, 51 

Fixed by gypsum, 182 

Contained in beet-root, 46 

maple juice, 46 

privies, 182 

stables, 182 

Furnishes nitrogen, 57 

Deductions of Boussingault con- 
cerning, 199 

Boussingault's deductions are 
erroneous, 200 

Is not an essential constituent 
of manure, 202 

Is always of use in manure, 203 

Loss from evaporation, 182 

Inorganic origin of, 73 

Product of decay, 42 

Properties of, 41 

Quantity absorbed by charcoal, 
56 

by decayed wood, 56 

In rain-water, 44 

In humus, 6 

In snow-water, 44 

Separated from soils by rain, 56 

Solubility of, 43 

Transformations of, 41 

Product of disease, 384 
Analysis of ashes of great import- 
ance, 203 
Animal food, preservation of, 304 

Life, dependent on plants, 57 

processes of, 167 

Matter, products of decay of, 57 

essential to nitrification, 

214 
Animals, excrements of, how form- 
ed, 50, 51 

Faeces of, contain little nitrogen, 
50 

Liquid excrements of, rich in 
nitrogen, 48 

Obtain their fundamental sub- 
stances from plants, 60 
Annual jjlants, how nourished, 99 
Anthoxanthum odoratum, acid 
in, 49 



Anthracite, 353 
Antidotes to poisons, 362 
Apatite, 117, 118 
Arable land, formation of, 82 
Argillaceoits earth, 111 
Aromatics, their influence on fer- 
mentation, 315 
Arsenious acid, action of, 361 
Ashes, analysis of various plants. 
See pages 68, 143, 150, 203, 
and Jlppendix to Part I., 230- 
254 

As a manure, 175 

Of bones, 185 

Of peat, 1S6 

Of coals, 178 

Of wood, 176 
Assimilation of carbon, 3-27 

Of carbonic acid and ammonia 
98 

Of hydrogen, 35-39 

Of nitrogen, 40-58 
Atmosphere, ammonia in, 43 

Carbonic acid in, 15 

Composition is invariable, 13 

Motion of, 19 
Atoms, motions of, 271 

Permanence in position of, 271 
AzoTizED matter in juices of plants 
102 

Substances, combustion of, 307 

B. 
Bark of trees viewed as exeremen- 

titious, 164 

Of fir, analysis of its ashes, 164 
Barley, analysis of its ashes, 150 

Experiment on, 22S 
Basalt, analysis of, 88 
Bases, alkaline in plants, on what 
their existence depends, 70 

Organic, 4, 71 

Oxvgen contained :ti, 67 

In plants, 65-81 

Substitution of, 68, 70 
Beans, analysis of ashes of, 143 

Contain casein, 135 

Nutritive power of, 134 
Beech, analysis of its ashes, 248 
Beer, 319 

Bavarian, 319 
Beet, analysis of, 12 

Ammonia contained in, 48 

From sandy soils, 104 
Bb:nignant disease, 380 



INDEX. 



39?. 



Benzoic acid, formed, 48 
Birch tree, ammonia in, 46 
Blood, analysis of its ashes, 142 

Action of chemical agents upon, 
374 

Its feeble resistance to exterior 
influences, 374 

Organic salts in, 357 

Its character, 367 
Blossoms, when produced, 32 

Increased, 98 
Bones, dust of, 178, 185 

Durability of, 185 

Gelatine in, 1S6 
BoRAcic acid, 78 
Bouquet of wines, 316 
Brandy from corn, 315 

Oil of, 316 
Brazil, wheat in, 114 
Brown Coal, 348 
Buckwheat, 223 

C. 

Cactus, 34 

Calcium, fluoride of, 119 

Chloride of, ISl 
Caoutchouc, in plants, 34 
Carbon, assimilation of, 3, 2S 

Of decaying substances, seldom 
affected by oxygen, 299 

Derived from air, 15 

In sea-water, 80 

Praduce of, in land, 12 

in beet, 12 

in straw, 12 

Restored to so'l, 32 

Received by itw^es, 16 
Carbonate of ammonia, contained 
in rain-water, 44 

Decomposed by gypsum, 180 

Of lime in caverns and vaults, 
94 
Carbonic acid in the atmosphere, 
15 

Changes in the leaves, 106 

Decomposed by plants, 19 

Decomposes soils, S3 

Emission of, at night, 26 

Evaporation of, 27 

Evolution Irom decaying b( dies, 
299-302 

From humus, 29 

respiration, 167 

woody fibre, 338 

Increase of, prevented, 16 



Carbonic \.cid — continued. 

Influei.ce of light on its decom- 
position, 106 
Carburetted hydrogen, with 

coal, 368 
Caverns, stalactites in, 94 
Charcoal, condenses ammonia, 56 

Promotes growth of plants, 1S5 
Chemical effects of light, 106 

Processes in the nutrition of 
vegetables, 2 

Transformations, 265, 275 
Chemistry, organic, what it is, 1 
Chloride of calcium, ISl 

Of potassium, 72 

Of sodium, its volatility, 79 
Clay slate, 88, 89, 118 
Clays, formation of, 90 

From porphyry, 90 

From felspar, 91 

Potash in. 111 
Clay, burned, how it acts as ma- 
nure, 55, 130 
Coal, formation of, 346-354 

Inflammable gases from, 353 

Of humus, 5 

Wood or brown, 348-352 
Colors of flowers, 41 
Combustion at low temperatures, 
300 

Of decayed wood, 342 

Induction of, 270, 306 

Respiration, viewed as, 169 

Spontaneous, 297 
Concretions from horses, 118 
Constituents of the blood exist in 
plants, 60 

The formation of, the main ob- 
ject of agriculture, 53 
Contagion, reproduction of, on 
what dependent, 377, 378 

Susceptibility to, how occasion- 
ed, 378 
Contagions, how produced, 376-373 

Propagation of, 377-384 
Contagious matters, action of, 376, 
379, 3S3 

Their efiects explained, 353, 371 

Life in, disproved, 353, 377 

Reproduction of 353, 377-37S 
Copper, oxide of, in clay slate, 118 
Corn, how cultivated in Italy, 114 
Corn brandy, 314 
Corrosive sublimatie, axrJivAi of 
361 



ii,9 



in; HEX. 



Cow-pox, action of virus of, 3S2 
Cow, urine of, analysis, 169, 2o5,"2-57 
Crops, rotation of, 136, 163 
Cultivation, its benefits, 19 

Different methods of, lOS 

Object of, 109 
Culture, art of, 93-122 
Cyanic acid, transformation of, 285 
Cyanogen, combustion of, 310 

Transformation of, 236 

D. 
Darwin on the formation of soils, 83 

Descriptions of the gold ores in 
Chili, 126 
Death, the source of life. 5S 
Decay, 295 

A source of ammonia, 42 

Of wood, 338 

And putrefaction, 273 
Decomposition, 267 
Diamond, its origin, 343 
Diastase, 118 

Contains nitrogen, 119 
Disease, how excited, 355-390 
Disintegration of rocks, 89 

Of ores, 126 
Dung of the nightingale, 262 

E. 
Ebony wood, oxygen and hydrogen 

. in, 24 
Elements of plants, 3 
Eremacausis, 295-310 

Analogous-to putrefaction, 301 

Arrested, 296 

Definition of, 295 

Necessary to nitrification, 307 

Of bodies containing nitrogen, 

307 
Of bodies destitute of nitrogen, 
303 
Ether, cenanthic, 316 
Excrementitious matter, pro- 
duction of, illustrated, 168 
Excrement, animal, its chemical 
nature, 169 
Of the cow, horse, &,c., 169, 
170,255-266 
Excrements, manure in which they 
are found, 1(J9 
Of animals, contain the same 
amount of nitrogen, as that 
present in the food, 169 



Excrements — continued. 

Of plants, 32 

Conversion of, into humus, 32 

Of man, amount of, 172, 173 
Excretion, organs of, 167 

Of plants, theory of, 32 



Fallow, 123-133 
Felspar, decomposition of, 90 
Analysis of, 86 
Various kinds of, 86 
Decomposed analysis of, 90 
Ferment, 289 
Fermentation, 287, 311-337 

Ascribed to fungi, and infusoria, 

326-337 
Of Bavarian beer, 319, 325 
Of beer, 311 
Gay-Lussac's experiments in, 

329 
Of sugar, 287 
Of vegetable juices, 288 
• Vinous, 311 
Of wort, 312 
Fertility of fields, how preserved, 

174 
Fibrin, 58, 135 

Fires, pldnts on localities of, 116 
Fir bark, analysis of its ashes, 164 

Wood, analysis of its ashes, 164 
Fishes in salt pans, 77 
Flesh, effect of salt on, 358 

Preserved under certain circum- 
stances, 330, 331 
Fluorine in ancient bones, 120 
Food, effect on products of plants, 
105 
Of young plants, 97 
Transformation and assimilation 

of, 32 
Knowledge of its composition 

essential, 133 
Undergoes combustion in tha 
body, 168 
Formation of wood, 103 
Franconia, caverns in, 94 
Fruit, increased, 98 
Ripening of, 38 

, changes attending, 99 

Fucus giganteus, 226 
Fungi, supposed to cause fermenta* 
tion, 326-337 



INDEX. 



397 



G. 

Gaseous substances in the lungs, 

effect of, 384 
Gasterostetjs aculeatus, in salt- 
pans, 77 
Gay-Lussac, his experiments, 327 
Germinatioiv of potatoes, 99 

Of grain, 102 
Glue, manure from, 179 
Glisten, conversion of, into yeast, 
322 

Decomposition of, 294 

Gas from, 311 
Grain-, germination of, 102 
Grapes, fermentation of, 311 

Juice of, differences in, IIS 

Potash in, 70 
Grauwacke, soil from, 113 
Guano, 4S, IGl, 174, 25S-2G2 
Gypsum, experiment with, 53 

Decomposed by carbonate of 
ammonia, ls2 

Decomposed by salt, 63 

Its influence, 53 

Use of, 1S2 

H. 
Hanover tobacco, 23S 
Havannah tobacco, analysis of its 

ashes, 238 
Hay, analysis of ashes, 150, 236 

Carbon in, 11 
Hessian and English weights and 

measures, 392 
Horse, urine of the, 169, 257, 258 

Concretions in the, 119 
Horse-dung, analysis of, 169, 231, 

237 
Humate of lime, quantity received 

by plants, 9 
Humic acid, 5 

Sometimes contains ammonia, 6 
Action of, 93 
Properties of, 5 
Is not contained in soils, 7 
Quantity received by plants, 9 
Insolubility of, 93 
HirMus, 5 

Action of, 93 
Analysis of, G 
Erroneous opinions concerning, 

7 
Action upon oxygen, 92, 93 
Coal of, 5 



Humus — continued. 

Conversion of woody fibre into 
338 

How produced, 5 

Its insolubility, 93 

Properties of, 5 

Sources of carbonic acid, 93 

Theory of its action, 93 
Hybernating animals, 100 
Hydrogen, assimilation of, 35-39 

Excess of in wood accounted 
for, 36 

Of decayed wood, 340-342 

Of plants, source of, 36 

Peroxide of, 270 
Hyett, Mr., on nitrate of soda, 223 

I. 
Ice, bubbles of gas in, 26 
Ingenhouss, his experiments, 21 
Ingredients of soil removed by 

crops, 148 
Inorganic constituents of plants, 

64-81 



Lava, soil from, 110 
Lead, salts of, compounds with or- 
ganic matter, 3G0 
Leaves, absorb carbonic acid, 16 

Ashes of, contain alkalies, 81 
Leaves of pine and lir — 

Cessation of their functions, 32 

Change color from absorption of 
oxygen, 38 

Decompose carljonic acid, 16 

Their office, Ifi 

Power of absf-rbirig nutriment, 
how increased, 30 
Life, notion, of, 369 
Light, absence o^ its eflect, 22 

Chemical efl'ects of, 105 

Influences decomposition of car- 
bonic acid, 105 
liiME, phos[)hate of, 176-178 
Lime, action of, 128-131 

LlME-PLANTS, 150 

Lime-tree yields sugar, 103 
Limestones, hydraulic, 91, 92, l.?0 

M. 
Magnesia, phosi)hate of, in seeda 

64, 65 
Manure, 105-167 



S'j3 



INDEX. 



Mantjre — continued. 

In the ashes of food burned in 

the body, US, 163 
Of bones, 176, 185 
The form of, important, 131 
Waste of, in England, 159 
Animal, yields ammonia, 169 
Maple juice, ammonia from. 46 

Trees, sugar of, 46 
Mesotype, properties of, 87 
> Miasm, defined, 384 
Morbid poisons, 361-375 
Mosses grow luxuriantly with green 

light, 107 
Motion, its influence on chemical 

forces, 272 
Mould, vegetable, 344 
Mouldering of bodies, 346 

N. 
Nitrate of soda as a manure, 223 
Nitric acid from ammonia, 218 

How formed 215-217 
Nitrification, 307-310 
Nitrogen, assimilation of, 40-57 
In excrements, 169 
In plants, 4 

Production of, the object of ag- 
riculture, 52 
Transformation of bodies con- 
taining, 307 
Nutrition, inorganic substances re- 
quisite in, 64 
Superfluous, how employed, 97 
Of young plants, 96 

O. 
Oaks, ashes of, 247 

Dwarf, 30 
Oak-wood, composition of, 247 
Odor of gaseous contagious matter, 

385 
(Enanthic ether, 316 
Organic acids, 140 

Decomposition of, 1 40 

Chemistry, 1 
Oxygen, absorption of, at night, 21 

Absorption of, by leaves, 38 

by respiration, 167 

Absorption of, by wood, 338-339 

Action upon woody fibre, ib. 

Emitted by leaves, 16 

In air, 13 " 

Consumption of, 14 

In water. 36 



Oxygex — continued. 

Separated during the formation 
of acids, 140 

Is furnished by the decomposi- 
tion of water, 36 

P. 
Peas, 232 

Ashes of, 143, 235, 250 
Ashes of straw, 238 
Peroxide of hydrogen, 270 
Phovolite, analysis of, 88 
Phosphates are constituents of 

plants, 64, 67, 176, 178 
Phosphoric acid in ashes of plants, 

64, 67, 176, 178 
Pine-tree ashes, 68, 238, 240, 242, 

248, 251, 252 
Plants absorb oxygen, 21 

Analysis of ashes, 143, 235-254 
Characterized by their principal 

mineral ingredients, 149 
Decompose carbonic acid, 26, 27 
Effect of, on rocks, 89 
Elements of, 4 
Exhalation of carbonic acid 

from, 21 
Functions of, 17 
Improve the air, 17 
Influence of gases on, 22 
Mineral ingredients of, 64, 81 

149 
Life of, connected with that of 

animals, 57 
Marine, food of, 157 
Millcy-juiced, in barren soils, 34 
Size of, proportioned to organs 

of nourishment, 30 
Rotation of, its advantage, 133 
Ploughing, its use, 128 
Poisoning, superficial, 359 

By sausages, 363 
Poisons, generated by disease, 351 
seq. 
Inorganic, 356 
Peculiar class of, 361 
Rendered inert by heat, 366 
Pompeii, bones from, 119 
Porphyry, by disintegrating, fornu 

clay, 89 
Potash, in grapes, 70 
Plants, "l 50 
Replaced l>y soda, 70 
Quantity in soils, 111 



INDEX. 



399 



Potatoes, germination of, Jippen- 

dix lo Part II., 391 
Purgative effect of salts explained, 

354 
Pus, globules in, 373 
Putrefaction, 25 

Communicated, 276, 363-37S 
Source of ammonia, 57 

of carbonic acid, 57 

Putrefying sausages, death from, 
364 
Their mode of action, 365 
Substances, their effect on 
wounds, 366 

• alkaline, 375 

acid, ib. 

R. 
Rain, necessity for, to furnish alka- 
lies to plants, 119 
Want of, or excess in, producing 
diseases in plants, 120 
Rain-water, contains ammonia, 43 
Removal of branches, effects of, 97 
Rhododendron ferrugineum, 97 
Ripening of fruit, 38 
Roots, excrements of, 73 
Rotation of crops, 133-L65 
Rye, 143, 232, 233 

Ashes of, 239, 249 



Saline plants, 71 

Salt, volatilization of, 79 

Salts, absorption of, 73 

Effects of, on the organism, 352 

■ on flesh, 354 

on the stomach, ib. 

Organic, in the blood, 353 
Passage of, through the lungs, 
352 
Salt-works, loss in, 79 
Sand, disintegrates when exposed 
to the action of carbonic acid, 
87 
Saturation, capacity of, 66 
Sausages, poisonous, 364 
Saussure, his experiments on air, 
15 
On the mineral ingredients of 
plants, 64, 242-248 
Science not opposed to practice, 

J 24 
Sea-water, analysis of, 79 



Sea-water — continued. 

Contains carbon, 80 

Contains ammonia, SO 
Silica, properties of, 84, 86 
Silicates, disintegration of, 155 
Silver, salts, poisonous effects of, 
359 

SiNAPIS ALBA, 3S7 

Size of plants proportioned tb or- 
gans of nourishment, 3U 
Snow-water, ammonia in, 43 
Soda, may replace potash, 70 
Soils, advantages of loosening, 12 1 

Analyses of, 263 

Exhaustion of, 113 

P^erruginous, improved, 95 

Fertile, of Vesuvius, 131 

Formation of, «2-92 

From lava, 131 

Imbibe ammonia, 51 

Physical properties of, 148 

Important, 152 

Exhaustion of, 1 t6 
Stagnant water, effect of, 95 
Stalactites in caverns, 93 
Starch, accumulation of, in plants, 
98 

Composition of, 37 

Development of plants influ' 
enced by, 99 

Product of, the life of plants, 2J 

In willows, 93 
Straw, analysis of, 12 

Of rye, 249 
Struve, experiments of, 113 
Substitution of bases, 66 
Succinic acid, 343 
Sugar, formed from acids, 137 

Composition of, 2S7 

Carbon in sugar, 12 

Contained in the maple tree, 45 

In Clerodendron fragrans, 193 

Development of plants, influ- 
ence on, 99 

Fermentation of, 287 

In beet-roots, 45 

Metamorphosis of, 288 

Product of, the life of plants, 21 

Transformation of, 275, xeq. 

When ])roduced, 31 
Sulphate of ammonia, well adapt 
ed to furnish plants with sul 
phur, 61 
Sulphates in water of springs, 61 



♦00 



INDEX. 



Sulphates — continued. 

Yield sulphur, 02 
Sulphur, crystallized, dimorphous, 

proportion of, to nitrogen in 

plants, 62 
Soui'ce of, in plants, 5S 
Sulphuric acid, action of, on soils, 

1S7 
Sulphurous acid arrests decay, 341 
Synaptas, 388 

T. 
Tables of Hessian and English 

weights and measures, 392 
Tannic aci;l, 36 
Tartaric acid, 36 

Converted into sugar, 37 

In wine, 298 
Teltow parsnip, 30 
Thenard, his experiments on yeast, 

290 
Tin, action on nitric acid, 268 
Tobacco juice, contains ammonia, 47 

Nitric acid, 48 

In Virginia, 113 
Transformation, by heat, 280 

Chemical, 26-5 

Of acetic acid, 2S0 

Of carbonic acid, 106 

Of meconic acid, 280 

Of bodies containing nitrogen, 
282 

Of bodies destitute of nitrogen, 
280 

Results of, 31 

Of wood, 281 

Of cyanic acid, 284 

Of cyanogen, 285 

Of gluten, 311 
Transplantation, effect of, 97 
Trees, diseases of, 102 

Require alkalies, 115 

U. 
Ulmin, 5 
Urea, converted into carbonate of 

ammonia, 48 
Urine, contains nitrogen, 43 

Its use as manure, 47 

Of men, 173 

Of horses, 169 

Human, analysis of, 173 

Of cows, 169 



V. 

Vaccination, its effect, 382 

Vegetable albumen, 48 

Mould, always contains carbon- 
ate of ammonia, 96 

Vegetation, tropical, 161 

Vesuvius, fertile soil of, 112 

Vines, juice of, yields ammonia, 46 

Vinous fermentation, 311 

Virginia, early products of its soils, 
114 

Virus, of small pox, 382 
Vaccine, 382 

Vital principle, how balanced in 
the blood, 371 

W. 
Water, carbonic acid of, absorbed, 
17 

Decomposes rocks, 113 

Composition of, 36 

Dissolves mould, 344 

Plants, their action upon, 26 

Rain, contains ammonia, 43 

required by gypsum, 55 

Salt, analysis of, 79 
Wavelite, 117 
Wheat, exhausts, 114 

Gluten of, 46 

Why it does not thrive on cer- 
tain soils, 115 

In Virginia, 114 

Red, 143 

White, 182 
Willows, growth of, 98 
Wine, effect of gluten upon, 318 

Fermentation of, 317 

Properties of, 318 

Substances in, 313 

Taste and smell, 314 

Varieties of, ih. 
WoAD, decomposition of, 294 
Wood, decayed, combustion of, 343 

Absorbs ammonia, 56 

Analysis of, 24 

Conversion of, into humus, 339 

Decay of, 338 

Requires air, ib. 

Decomposition of, 260, 295 

Effect of moisture and air on, 338 

Elemeiits of, 339 

Formation of, 10?, 

Source of its carbon, 12 

Transformation of, 231 



INDEX 40J 

Wood-coal, how produced, 34S 

Analysis of, 348, 349 Y. 

Woody fibre, changes in, 33S Yeast, 290 

Composition of, 339 Destroyed, 313 

Decomposition of, 338 Experiments on, 290 

Difference between it and wood. Formed, 312 

24 Its mode of action, 292 

Formation of, 20 Its production, 336 

Moist evolves carbonic acid, 338 Two kinds of, 320, $eq. 

Mould from, 343 
Wort, fermentation of, 319 Z. 

Wounds, etlect of putrefying sub- Zeolite, analysis of, 87 
stances on, 366 



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